EX-99. CERT CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002 I, Terry K. Glenn, President of MuniYield New Jersey Insured Fund, Inc., certify that: 1. I have reviewed this report on Form N-CSR of MuniYield New Jersey Insured Fund, Inc. (the "Fund"); 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; and 3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations, changes in net assets, and cash flows (if the financial statements are required to include a statement of cash flows) of the Fund as of, and for, the periods presented in this report; 4. The Fund's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-2(c) under the Investment Company Act of 1940) for the Fund and have: a) designed such disclosure controls and procedures to ensure that material information relating to the Fund, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared; b) evaluated the effectiveness of the Fund's disclosure controls and procedures as of a date within 90 days prior to the filing date of this report (the "Evaluation Date"); and c) presented in this report our conclusions about the effectiveness of the disclosure controls and procedures based on our evaluation as of the Evaluation Date; 5. The Fund's other certifying officers and I have disclosed, based on our most recent evaluation, to the Fund's auditors and the audit committee of the Fund's board of directors (or persons performing the equivalent functions): a) all significant deficiencies in the design or operation of internal controls which could adversely affect the Fund's ability to record, process, summarize, and report financial data and have identified for the Fund's auditors any material weaknesses in internal controls; and b) any fraud, whether or not material, that involves management or other employees who have a significant role in the Fund's internal controls; and 6. The Fund's other certifying officers and I have indicated in this report whether or not there were significant changes in internal controls or in other factors that could significantly affect internal controls subsequent to the date of our most recent evaluation, including any corrective actions with regard to significant deficiencies and material weaknesses. Date: June 23, 2003 /s/ Terry K. Glenn Terry K. Glenn, President of MuniYield New Jersey Insured Fund, Inc. EX-99. CERT CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002 I, Donald C. Burke, Chief Financial Officer of MuniYield New Jersey Insured Fund, Inc., certify that: 1. I have reviewed this report on Form N-CSR of MuniYield New Jersey Insured Fund, Inc. (the "Fund"); 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; 3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations, changes in net assets, and cash flows (if the financial statements are required to include a statement of cash flows) of the Fund as of, and for, the periods presented in this report; 4. The Fund's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-2(c) under the Investment Company Act of 1940) for the Fund and have: a) designed such disclosure controls and procedures to ensure that material information relating to the Fund, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared; b) evaluated the effectiveness of the Fund's disclosure controls and procedures as of a date within 90 days prior to the filing date of this report (the "Evaluation Date"); and c) presented in this report our conclusions about the effectiveness of the disclosure controls and procedures based on our evaluation as of the Evaluation Date; 5. The Fund's other certifying officers and I have disclosed, based on our most recent evaluation, to the Fund's auditors and the audit committee of the Fund's board of directors (or persons performing the equivalent functions): a) all significant deficiencies in the design or operation of internal controls which could adversely affect the Fund's ability to record, process, summarize, and report financial data and have identified for the Fund's auditors any material weaknesses in internal controls; and b) any fraud, whether or not material, that involves management or other employees who have a significant role in the Fund's internal controls; and 6. The Fund's other certifying officers and I have indicated in this report whether or not there were significant changes in internal controls or in other factors that could significantly affect internal controls subsequent to the date of our most recent evaluation, including any corrective actions with regard to significant deficiencies and material weaknesses. Date: June 23, 2003 /s/ Donald C. Burke Donald C. Burke, Chief Financial Officer of MuniYield New Jersey Insured Fund, Inc. Exhibit 99.1350CERT Certification Pursuant to Section 906 of the Sarbanes Oxley Act I, Terry K. Glenn, President of MuniYield New Jersey Fund, Inc. (the "Fund"), certify that: 1. The N-CSR of the Fund (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Fund. Dated: June 23, 2003 /s/ Terry K. Glenn Terry K. Glenn, President of MuniYield New Jersey Fund, Inc. A signed original of this written statement required by Section 906 has been provided to MuniYield New Jersey Fund, Inc. and will be retained by MuniYield New Jersey Fund, Inc. and furnished to the Securities and Exchange Commission or staff upon request. Exhibit 99.1350CERT Certification Pursuant to Section 906 of the Sarbanes Oxley Act I, Donald C. Burke, Chief Financial Officer of MuniYield New Jersey Fund, Inc. (the "Fund"), certify that: 1. The N-CSR of the Fund (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Fund. Dated: June 23, 2003 /s/ Donald C. Burke Donald C. Burke, Chief Financial Officer of MuniYield New Jersey Fund, Inc. A signed original of this written statement required by Section 906 has been provided to MuniYield New Jersey Fund, Inc. and will be retained by MuniYield New Jersey Fund, Inc. and furnished to the Securities and Exchange Commission or staff upon request.