This study examined ethnic differences in response to antidepressant treatment. One hundred eighteen depressed HIV-positive patients entered an eight-week controlled trial of fluoxetine. Nineteen percent were black and 14 percent were Latino; the remaining two-thirds were white. Attrition was greater among Latinos than either blacks or whites. Black patients were more likely than whites to be nonresponders to fluoxetine. Latinos were more likely to respond to placebo compared with blacks and whites. Ethnic groups did not differ in the presence of treatment-emergent side effects.