Forty-one patients who had failed to respond to 8 weeks of treatment with 20 mg of fluoxetine were randomly assigned to one of three treatments for 4 weeks: 40-60 mg/day of fluoxetine, 20 mg/day of fluoxetine plus 25-50 mg/day of desipramine, and 20 mg/day of fluoxetine plus 300-600 mg/day of lithium. Patients treated with high-dose fluoxetine (N = 15) did significantly better than patients treated with fluoxetine plus lithium (N = 14) and those treated with fluoxetine plus desipramine (N = 12). High-dose fluoxetine was the most effective treatment among partial responders to previous treatment, but high-dose fluoxetine and fluoxetine plus lithium were the most effective treatments among nonresponders.