Medicaid/SCHIP Optional Coverage for Young Adults Act of 2003 - Amends titles XIX (Medicaid) and XXI (State Children's Health Insurance) (SCHIP) of the Social Security Act to give States the option of providing SCHIP and Medicaid coverage, with an enhanced matching rate, to low-income youth up to age 23.
Directs the Secretary to provide for grants to small and rural States in order to enable them to implement expansions of eligibility for children and young adults under SSA titles XIX and XXI.