OBJECTIVE: Use of electroconvulsive therapy (ECT) in the Medicare population was examined to document trends and variations in the rate of use, expenditures, and patterns of treatment. METHODS: Medicare part B enrollment and claims data were used for a 5 percent nationally representative sample of Medicare beneficiaries for calendar years 1987 through 1992. Descriptive and multivariate analyses were performed. RESULTS: Weighted results showed that nationally the number of Medicare beneficiaries treated with ECT increased from 12,000 in 1987 to 15,560 in 1992. The rate of ECT use per 10,000 Medicare beneficiaries also increased from 4.2 to 5.1. Increases in use occurred among women, whites, and the disabled population (under age 65). Males, nonwhites, and the elderly did not share in the increase. Utilization and expenditure data showed an increase in outpatient ECT and a decrease in inpatient use between 1987 and 1992. The share of Medicare part B ECT expenditures in the outpatient setting increased steadily, from 7 percent in 1987 to 16 percent in 1992. Patients averaged eight ECT treatments, ranging from 6.7 in the West to 8.3 in the Northeast. CONCLUSIONS: The findings document that after a long period of declining use in the United States, ECT use in the Medicare population increased between 1987 and 1992. The analysis also documents a shift toward increasing use of outpatient ECT.