Major depressive disorder in HIV-positive persons is often not diagnosed, and poorly treated. The effect of depression screening on case detection, and rates of antidepressant prescription is unknown.We assessed 368 participants for major depressive disorder, and provided clinicians with the results. Four weeks later, we abstracted information from the charts of the depressed patients to ascertain if they received antidepressants. We also randomly sampled the charts of 368 non-screened patients, to ascertain whether clinicians had diagnosed and prescribed antidepressant treatment.Major depressive disorder was identified in 17.9 % of the screened group, and in 2.1 % of the non-screened group [OR = 9.65, CI = (4.54-20.50)]. The screened individuals were 7.8 times more likely to receive antidepressants (95 % CI = 3.04-20.24). Identification of major depressive disorder by clinicians in HIV settings remains poor. However, routine screening can improve case detection rates and the proportion of patients receiving antidepressants.