Comprehensive Immunosuppressive Drug Coverage for Transplant Patients Act of 2003

Comprehensive Immunosuppressive Drug Coverage for Transplant Patients Act of 2003 - Amends title XVIII (Medicare) of the Social Security Act (SSA), as amended by the Medicare, Medicaid, and SCHIP Benefits Improvement and Protection Act of 2000, to remove time limitations on the coverage of immunosuppressive drugs for individuals who have received organ transplants. (Current law provides coverage for such drugs only for certain time periods after the transplant procedure.)

Amends SSA title II (Old Age, Survivors and Disability Insurance) (OASDI) to: (1) continue entitlement to prescription drugs used in immunosuppressive therapy furnished to an individual who receives a kidney or other organ transplant for which payment is made under Medicare; and (2) extend Medicare secondary payer requirements for end stage renal disease beneficiaries.

Amends the Public Health Service Act, the Employee Retirement Income Security Act of 1974 (ERISA), and the Internal Revenue Code to set forth requirements for group health plans to provide coverage of immunosuppressive drugs.