<Page>
Exhibit 21
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
MAGELLAN HEALTH SERVICES, INC.
LIST OF SUBSIDIARIES
<Table>
<Caption>
- --------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- --------------------------------------------------------------------------- ----------------------- ----------
Care Management Resources, Inc. Florida C
Green Spring Health Services, Inc. Delaware C
SUBSIDIARIES:
Advantage Behavioral Systems, Inc. Pennsylvania C
SUBSIDIARY:
Resource Day Treatment Center Pennsylvania NP
AdvoCare of Tennessee, Inc. Tennessee C
SUBSIDIARY:
Premier Holdings, Inc. Tennessee C
SUBSIDIARY:
Magellan - PBS, LLC LLC
Premier Behavioral Systems of Tennessee, LLC(1) Tennessee LLC
Allied Specialty Care Services, LLC Delaware LLC
SUBSIDIARIES:
Vivra, Inc. Nevada C
SUBSIDIARIES:
Vivra Heart Services, Inc. Nevada C
Vivra Network Services, Inc. Florida C
PHP Holdings, Inc. Colorado C
iHealth Technologies, LLC(2) Delaware LLC
SUBSIDIARY:
CAI Merger Corporation Delaware C
Ceres Behavioral Healthcare Systems, LLC(3) Oregon LLC
New GPA, Inc.(4) Delaware C
</Table>
- ----------------------
(1) 50% owned by Premier Holdings, Inc.
(2) Formed on 2/12/01. iHealth Technologies, Inc. merged into this LLC
on 2/16/01.
(3) 97% owned by Green Spring Health Services, Inc.
(4) Formerly known as Group Practice Affiliates, Inc. 100% by Green Spring
Health Services, Inc. by virtue of a stock transfer from Green Spring
Health Services, Inc. on 4/15/99).
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- --------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- --------------------------------------------------------------------------- ----------------------- ----------
SUBSIDIARIES:
GPA Pennsylvania, Inc. Pennsylvania C
Novapsy Clinic, LLC(5) Virginia LLC
Green Spring of Pennsylvania, Inc. Pennsylvania C
Magellan Behavioral of Michigan, Inc. Michigan C
Magellan Behavioral Health of New Jersey, LLC New Jersey LLC
Magellan Capital, Inc. Delaware C
Managed Care Services Mainstay of Central Pennsylvania, Inc. Pennsylvania C
Maryland Health Partners, LLC(6) Maryland LLC
Vista Behavioral Health Plans, Inc. California C
Human Affairs International, Incorporated Utah C
SUBSIDIARIES:
Human Affairs of Alaska, Inc. Alaska C
Human Affairs International of California California C
Human Affairs International of Pennsylvania, Inc. Pennsylvania C
MBH Capital, Inc.(7) Delaware C
SUBSIDIARIES:
CMCI, Inc. Nevada C
CMFC, Inc. Nevada C
Magellan Behavioral Health, Inc. Delaware C
SUBSIDIARIES:
Magellan Behavioral Health of Ohio, Inc. Ohio C
Magellan Behavioral Health of Washington, Inc. Washington C
MBH of Puerto Rico Puerto Rico C
MCI/Magellan Partners, L.L.C.(8) Delaware LLC
Merit Behavioral Care Corporation Delaware C
SUBSIDIARIES:
</Table>
- ----------------------
(5) 50% owned by Group Practice Affiliates, Inc.-expected to close operations
on 2/28/01
(6) 50% owned by Green Spring Health Services, Inc.; 50% owned by CMG Health,
Inc., a direct subsidiary of Merit Behavioral Care Corporation.
(7) Charter Behavioral Corporation was renamed MBH Capital, Inc. on
2/15/01and Desert Springs Hospital, Inc. merged with this corporation
(8) 50% owned by Magellan Behavioral Health, Inc.
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- --------------------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- --------------------------------------------------------------------------------------- ----------------------- ----------
American Biodyne, Inc. Delaware C
SUBSIDIARIES:
AGCA, Inc. Pennsylvania C
SUBSIDIARIES:
AGCA Headquarters Limited Partnership(9) Pennsylvania LP
AGCA New York, Inc. New York C
SUBSIDIARIES:
AGCA IPA of New York, Inc. New York C
MBC Health Care of New York, Inc., a New New York C
York Independent Practice Association
MBC Health Services of New York, Inc., a New New York C
York Independent Practice Association
MBC of New York, Inc., a New York New York C
Independent Practice Association
MBC Providers of New York, Inc., a New New York C
York Independent Practice Association
U.S. IPA Providers, Inc. New York C
Alliance Health Systems, Inc.(10) Indiana C
Arizona Biodyne, Inc. Arizona C
Hawaii Biodyne, Inc. Hawaii C
Louisiana Biodyne, Inc. Louisiana C
Magellan HRSC, Inc.(11) Ohio C
MBC Federal Programs, Inc. Delaware C
MBC of New Mexico, Inc. New Mexico C
Merit Behavioral Care of Florida, Inc. Florida C
Merit Behavioral Care of Illinois, Inc. Illinois C
Merit Behavioral Care of Massachusetts, Inc. Massachusetts C
Magellan Behavioral Health of Pennsylvania, Inc. Pennsylvania C
(f/k/a Merit Behavioral Care of
Pennsylvania, Inc.)
Vermont Biodyne, Inc. Vermont C
</Table>
- ----------------------
(9) 15% owned by AGCA, Inc.
(10) 80% owned by American Biodyne, Inc.
(11) Formerly known as Merit Behavioral Care Systems Corporation
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- ----------------------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- ----------------------------------------------------------------------------------------- ----------------------- ----------
Benesys Doctors, P.A. Texas
CMG Health, Inc. Maryland C
SUBSIDIARIES:
Choice Behavioral Health Partnership(12) Virginia GP
CMG Health of New York, Inc. New York C
Maryland Health Partners, LLC(13) Maryland LLC
Montana Community Partners, Inc.(14) Montana C
Continuum Behavioral Care, LLC(15) Rhode Island LLC
Continuum Behavioral Healthcare Corporation Delaware C
SUBSIDIARY:
Spectrum-Continuum Management Services of New York, LLC(16) Delaware LLC
SUBSIDIARY:
Spectrum-Continuum IPA Providers of New York, LLC(17) Delaware LLC
EMHC-MBC of New York, LLC(18) New York LLC
EMHC/MBC IPA Providers of New York, LLC(19) New York LLC
EMHC-MBC Services of New York, LLC(20) New York LLC
Group Plan Clinic, Inc. Texas C
MBC Health Providers of Texas, Inc. Texas C
MBC of America, Inc. Delaware C
SUBSIDIARIES:
EMHC/MBC IPA Providers of New York, LLC(21) New York LLC
EMHC-MBC Services of New York, LLC(22) New York LLC
</Table>
- ----------------------
(12) 50% owned by CMG Health, Inc.
(13) 50% owned by CMG Health, Inc.; 50% owned by Green Spring Health
Services, Inc.
(14) 55% owned by CMG Health, Inc.
(15) 50% owned by Merit Behavioral Care Corporation
(16) 50% owned by Continuum Behavioral Healthcare Corporation
(17) 100% owned by Spectrum-Continuum Management Services of New York, LLC
(18) 79.8% owned by Merit Behavioral Care Corporation
(19) 99% owned by EMHC-MBC of New York, LLC; 1% owned by MBC of America, Inc.
(20) 99% owned by EMHC-MBC of New York, LLC; 1% owned by MBC of America, Inc.
(21) 1% owned by MBC of America, Inc.; 99% owned by EMHC-MBC of New York, LLC
(22) 1% owned by MBC of America, Inc.; 99% owned by EMHC-MBC of New York, LLC
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- ----------------------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- ----------------------------------------------------------------------------------------- ---------------------- ----------
Empire Community Delivery Systems, LLC(23) New York LLC
MBC Management Services of New York, LLC(24) New York LLC
MBC of Nebraska, L.L.C.(25) Nebraska LLC
MBC of Tennessee, Inc. Tennessee C
MBC of Tennessee, LLC(26) Tennessee LLC
MBC/IPA Providers of New York, LLC(27) New York LLC
Royal Health Care, LLC(28) New York LLC
MBC of North Carolina, LLC North Carolina LLC
MBC of Tennessee, LLC(29) Tennessee LLC
SUBSIDIARY:
Community Sector Systems, Inc.(30) Washington C
Merit Behavioral Care Corporation of Iowa Iowa C
Merit Health Insurance Company Illinois C
SUBSIDIARY:
Orion Life Insurance Company Delaware C
Merit Holdings Corp. Delaware C
SUBSIDIARIES:
MBC National Service Corporation Delaware C
Merit Behavioral Care of Maryland, Inc. Maryland C
Merit INROADS Behavioral Health Services, LLC(31) Delaware LLC
SUBSIDIARIES:
Merit INROADS Behavioral Health Services of
Illinois, LLC(32) Illinois LLC
</Table>
- ----------------------
(23) 16.667% owned by MBC of America, Inc.
(24) 80.2 % owned by MBC of America, Inc.
(25) 50% owned by MBC of America, Inc.
(26) MBC of America, Inc and Merit Behavioral Care Corporation serve as sole
members
(27) 80.2% owned by MBC of America, Inc.
(28) 50% owned by MBC of America, Inc.
(29) Merit Behavioral Care Corporation and MBC of America, Inc. serve as sole
members
(30) 19.9 % owned by MBC Washington Systems, Inc.
(31) 99% owned by Merit Holdings Corp.; 1% owned by Merit Behavioral Care of
Illinois, Inc.
(32) 99% owned by Merit INROADS Behavioral Health Services, LLC; 1% owned by
Merit Behavioral Care Systems Corporation
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- ----------------------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- ----------------------------------------------------------------------------------------- ----------------------- ----------
INROADS Behavioral Health Services of Texas, L.P.(33) Texas LP
MeritChoice, Ltd.(34) Pennsylvania LP
PPC Group, Inc. Delaware C
SUBSIDIARIES:
Merit Behavioral Care of California, Inc. Missouri C
P.P.C., Inc. Missouri C
SUBSIDIARY:
Personal Performance Consultants of New York, Inc. New York C
Washton Institute, Inc. New York C
Tennessee Behavioral Health, Inc. TN C
Magellan Behavioral Health of Texas, Inc. Texas C
Magellan CBHS Holdings, Inc. Delaware C
SUBSIDIARIES:
Behavioral Health Systems of Indiana, Inc. Indiana C
SUBSIDIARIES:
The Charter Behavioral Health System of Northwest Indiana, LLC(35) Delaware LLC
CCM, Inc.(36) Nevada C
Charter Alvarado Behavioral Health System, Inc. California C
Charter Bay Harbor Behavioral Health System, Inc. Florida C
Charter Behavioral Health System of Athens, Inc. Georgia C
Charter Behavioral Health System of Central Georgia, Inc. Georgia C
Charter Behavioral Health System of Charleston, Inc. South Carolina C
Charter Behavioral Health System of Charlottesville, Inc. Virginia C
Charter Behavioral Health System of Chicago, Inc. Illinois C
Charter Behavioral Health System of Columbia, Inc. Missouri C
</Table>
- ----------------------
(33) 99% owned by Merit INROADS Behavioral Health Services, LLC; 1%
owned by Merit Behavioral Care Systems Corporation
(34) 50% owned by Merit Holdings Corp.
(35) 5% owned by Behavioral Health Systems of Indiana, Inc.; 95% owned by
Charter Indiana BHS Holding, Inc.
(36) 50% owned by Magellan CBHS Holdings, Inc.; 50% owned by CMCI, Inc.
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- ----------------------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- ----------------------------------------------------------------------------------------- ----------------------- ----------
Charter Behavioral Health System of Corpus Christi, Inc. Texas C
Charter Behavioral Health System of Dallas, Inc. Texas C
Charter Behavioral Health System of Delmarva, Inc. Maryland C
Charter Behavioral Health System at Fair Oaks, Inc. New Jersey C
Charter Behavioral Health System of Fort Worth, Inc. Texas C
Charter Behavioral Health System at Hidden Brook, Inc. Maryland C
Charter Behavioral Health System of Jackson, Inc. Mississippi C
Charter Behavioral Health System of Lafayette, Inc. Louisiana C
SUBSIDIARY:
The Charter Cypress Behavioral Health System, L.L.C.(37) Tennessee LLC
Charter Behavioral Health System of Lake Charles, Inc. Louisiana C
Charter Behavioral Health System of Massachusetts, Inc. Massachusetts C
SUBSIDIARY:
WESTWOOD/PEMBROKE HEALTH SYSTEM LIMITED PARTNERSHIP(38) Massachusetts LP
Charter Behavioral Health System of Mississippi, Inc. Mississippi C
Charter Behavioral Health System of Nashua, Inc. New Hampshire C
Charter Behavioral Health System of Nevada, Inc. Nevada C
Charter Behavioral Health System of New Mexico, Inc. New Mexico C
SUBSIDIARY:
The Charter Heights Behavioral Health System Limited Partnership(39) Delaware LP
Charter Behavioral Health System of Paducah, Inc. Kentucky C
Charter Behavioral Health System at Potomac Ridge, Inc. Maryland C
Charter Behavioral Health of Puerto Rico, Inc. Georgia C
Charter Behavioral Health System of San Jose, Inc. California C
Charter Behavioral Health System of Toledo, Inc. Ohio C
Charter Canyon Behavioral Health System, Inc. Utah C
Charter Canyon Springs Behavioral Health System, Inc. California C
Charter Centennial Peaks Behavioral Health System, Inc. Colorado C
Charter Fairmount Behavioral Health System, Inc. Pennsylvania C
</Table>
- ----------------------
(37) 50% owned by Charter Behavioral Health System of Lafayette, Inc.
(38) Approximately 97.5% owned by Charter Behavioral Health System of
Massachusetts, Inc.
(39) 67% owned by Charter Behavioral Health System of New Mexico, Inc.
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- ------------------------------------------------------------------------------------------ ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- ------------------------------------------------------------------------------------------ ----------------------- ----------
Charter Fenwick Hall Behavioral Health System, Inc. South Carolina C
Charter Forest Behavioral Health System, Inc. Louisiana C
Charter Grapevine Behavioral Health System, Inc. Texas C
Charter Hospital of Mobile, Inc. Alabama C
Charter Hospital of Santa Teresa, Inc. New Mexico C
Charter Hospital of St. Louis, Inc. Missouri C
Charter Indiana BHS Holding, Inc. Indiana C
SUBSIDIARIES:
The Charter Behavioral Health System of Northwest Indiana, LLC(40) Delaware LLC
Charter Lakehurst Behavioral Health System, Inc. New Jersey C
Charter Linden Oaks Behavioral Health System, Inc. Illinois C
SUBSIDIARY:
Naperville Psychiatric Ventures (41) Illinois GP
Charter Meadows Behavioral Health System, Inc. Maryland C
Charter Medical - Clayton County, Inc. Georgia C
Charter Medical of East Valley, Inc. Arizona C
Charter Medical Leasing Limited United Kingdom C
Charter Medical - Long Beach, Inc. California C
Charter Medical of Puerto Rico, Inc. Puerto Rico C
Charter Milwaukee Behavioral Health System, Inc. Wisconsin C
Charter MOB of Charlottesville, Inc. Virginia C
SUBSIDIARY:
Mental Healthsource, L.L.C.(42) Virginia LLC
Charter North Behavioral Health System, Inc. Alaska C
Charter North Counseling Center, Inc. Alaska C
Charter North Star Behavioral Health System, L.L.C.(43) Tennessee LLC
Charter Northridge Behavioral Health System, Inc. North Carolina C
</Table>
- ----------------------
(40) 95% owned by Charter Indiana BHS Holding, Inc.; 5% owned by Behavioral
Health Systems of Indiana, Inc.
(41) 75% owned by Charter Linden Oaks Behavioral Health System, Inc.
(42) 50% owned by Charter MOB of Charlottesville, Inc. (previously 50% owned
by Charter Behavioral Health System of Central Virginia, Inc. who merged in
Charter MOB of Charlottesville on 1/28/00)
(43) 57% owned by Magellan CBHS Holdings, Inc.
<Page>
C=corporation; CLS=company limited by shares; GP=general partnership;
LLC=limited liability company; LP=limited partnership; MC=medical
corporation; NP=non-profit corporation; PC=professional corporation;
ULLC=unlimited liability company 12/31/01 12:39 PM
<Table>
<Caption>
- ----------------------------------------------------------------------------------------- ----------------------- ----------
ENTITY NAME: JURISDICTION OF ENTITY
DOMICILE: TYPE:
- ----------------------------------------------------------------------------------------- ----------------------- ----------
SUBSIDIARY:
Holly Hill/Charter Behavioral Health System, L.L.C.(44) Tennessee LLC
Charter Park Hospital Limited United Kingdom C
Charter Plains Behavioral Health System, Inc. Texas C
Charter Westbrook Behavioral Health System, Inc. Virginia C
SUBSIDIARY:
CPS Associates, Inc. Virginia C
Charter Woods Behavioral Health System, Inc. Alabama C
Florida Health Facilities, Inc. Florida C
Golden Isle Assurance Company Ltd. Bermuda C
Plymouth Insurance Company, Ltd. Bermuda C
Magellan Public Solutions, Inc.(45) Delaware C
SUBSIDIARIES:
KidsCareNet of Milwaukee, LLC(46) Wisconsin LLC
Magellan Public Network, Inc. Delaware C
Correctional Behavioral Solutions of Indiana, Inc. Indiana C
Correctional Behavioral Solutions of New Jersey, Inc. New Jersey C
Correctional Behavioral Solutions of Ohio, Inc. Ohio C
Magellan Specialty Health, Inc. Delaware C
</Table>
NOTE: The ownership interest in each non-indented entity is directly-held
by Magellan Health Services, Inc.; the ownership interest in each
indented entity is directly-held by the preceding non-indented
entity. The percentage of ownership in each entity is 100% unless
otherwise noted in a footnote.
- ----------------------
(44) 50% owned by Charter Northridge Behavioral Health System, Inc.
(45) Correctional Behavioral Solutions, Inc. merged into parent on 9/17/01
(46) 50% owned by Magellan Public Solutions, Inc.