Exhibit 21.1 EXHIBIT D Subsidiaries of the Company Brandywine Operating Partnership, a Delaware limited partnership Witmer Operating Partnership I, L.P., a Delaware limited partnership Fifteen Horsham, L.P., a Pennsylvania limited partnership C/N Oaklands Limited Partnership I, a Pennsylvania limited partnership Newtech IV Limited Partnership, a Pennsylvania limited partnership Newtech III Limited Partnership, a Pennsylvania limited partnership LC/N Keith Valley Limited Partnership I, a Pennsylvania limited partnership LC/N Horsham Limited Partnership, a Pennsylvania limited partnership Nichols Lansdale Limited Partnership III, a Pennsylvania limited partnership C/N Leedom Limited Partnership II, a Pennsylvania limited partnership C/N Oaklands Limited Partnership III, a Pennsylvania limited partnership Iron Run Limited Partnership V, a Pennsylvania limited partnership C/N Iron Run Limited Partnership III, a Pennsylvania limited partnership Brandywine TB I, L.P., a Pennsylvania limited partnership Brandywine TB II, L.P., a Pennsylvania limited partnership Brandywine TB III, L.P., a Pennsylvania limited partnership Brandywine Dominion, L.P., a Pennsylvania limited partnership Brandywine P.M., L.P., a Pennsylvania limited partnership Brandywine I.S., L.P., a Pennsylvania limited partnership Brandywine F.C., L.P., a Pennsylvania limited partnership Brandywine Norriton, L.P., a Pennsylvania limited partnership Brandywine Realty Partners, a Pennsylvania general partnership Brandywine Holdings I, Inc., a Pennsylvania corporation Brandywine Holdings II, Inc., a Pennsylvania corporation Brandywine Holdings III, Inc., a Pennsylvania corporation Brandywine Realty Services Corporation, a Pennsylvania corporation Brandywine Main Street, LLC, a Delaware limited liability company Brandywine Acquisitions, LLC, a Delaware limited liability company 1100 Brandywine, LLC, a Delaware limited liability company Brandywine Leasing, LLC, a Delaware limited liability company Brandywine Trenton Urban Renewal, LLC, a Delaware limited liability company Brandywine New Brunswick Urban Renewal, LLC, a Delaware limited liability company Brandywine TB I, LLC, a Pennsylvania limited liability company Brandywine TB II, LLC, a Pennsylvania limited liability company Brandywine TB III, LLC, a Pennsylvania limited liability company Brandywine Witmer, LLC, a Pennsylvania limited liability company Brandywine Dominion, LLC, a Pennsylvania limited liability company Brandywine P.M., LLC, a Pennsylvania limited liability company Brandywine I.S., LLC, a Pennsylvania limited liability company Brandywine F.C., LLC, a Pennsylvania limited liability company Brandywine Norriton, LLC, a Pennsylvania limited liability company Christiana Center Operating Company I, LLC, a Delaware limited liability company Christiana Center Operating II, LLC, a Delaware limited liability company Four Tower Bridge Associates, a Pennsylvania limited partnership Five Tower Bridge Associates, a Pennsylvania limited partnership Plymouth Meeting General Partnership, a Pennsylvania general partnership 1000 Chesterbrook Boulevard Partnership, a Pennsylvania general partnership Interstate 202 General Partnership, a Pennsylvania general partnership