This study focused on persons 65 years of age and over who were dually entitled to Medicare and Medicaid in 1978. The paper examines their age, sex, and race characteristics, and their Medicare utilization and mortality rates in comparison to persons eligible for Medicare only. The study showed that the group entitled to both Medicare and Medicaid was relatively much older than those with Medicare only, with a mean age of 76.6 years compared to 73.6 years. In the group entitled to both Medicare and Medicaid, the proportion of persons of minority races was four times as great as the proportion in the remaining population. Nevertheless, nearly three out of four persons entitled to both programs were white. In the group with dual eligibility, 71 percent were women, compared to only 59 percent in the Medicare-only population. Thus, the dually covered group may be characterized as being relatively older than other Medicare enrollees, largely composed of white persons and women, and as having a higher proportion of minority persons than the general population. The study showed that a much higher proportion of dually entitled persons were users of the Medicare program than were persons eligible for Medicare only. On a per-enrollee basis, reimbursement was substantially higher for those dually eligible. The study also found differences in the diagnostic conditions of the dually entitled. The data indicate (after being standardized for age) that the death rate was 50 percent higher for the dually entitled. This difference in mortality is partly attributable to the relatively high mortality rates for the medically needy; nonetheless, the mortality rate for the dually entitled who also received cash assistance was 20 percent higher than those for other Medicare enrollees. The excess mortality among this group was notably higher for the age group 65-69, with a 50 percent excess mortality, and for the age group 70-79, the excess mortality was 30 percent. Thus, the dually entitled, in general, experience higher mortality rates than those with Medicare only, and that fact very likely explains to a large extent the higher utilization rates found for the dually entitled in this study. The paper concludes by raising some possible consequences of either Medicare or Medicaid coverage being altered or tightened.