Medicare Geographic Equity in Reimbursement Act of 2003 - Amends title XVIII (Medicare) of the Social Security Act to instruct the Secretary of Health and Human Services to establish a system for making adjustments to the amount of payment made to entities and individuals for items and services provided under the original Medicare fee-for-service program, with specified formulae for States whose average yearly per beneficiary amount for the most recent recorded year is eight percent or more below the average of contiguous States.