Elderly women and men have different patterns of disease and utilize health services differently. This essay examines the extent to which Medicare covers the specific conditions and services associated with women and men. Elderly women experience higher rates of poverty than elderly men; consequently, elderly women are especially likely to be unable to pay high out-of-pocket costs for health care. Using a new method for simulating out-of pocket costs, the Illness Episode Approach, the essay shows that Medicare provides better coverage for illnesses which predominate among men than for those which predominate among women. In addition, women on Medicare who supplement their basic coverage by purchasing a typical private insurance "Medigap" policy do not receive as much of an advantage from their purchases as do men. The calculations also show that the Medicare Catastrophic Coverage Act would have had little impact on the gender gap in financial vulnerability.