The objective of the study was to assess the effectiveness of group counseling, using a problem-solving therapy approach, on reducing depressive symptoms and increasing prenatal disclosure rates of HIV status among HIV-positive pregnant women living in Dar es Salaam, Tanzania. A randomized controlled trial was performed comparing a six-week structured nurse-midwife facilitated psychosocial support group with the standard of care. Sixty percent of women in the intervention group were depressed post-intervention, versus 73% in the control group [Relative Risk (RR) = 0.82, 95% confidence interval (CI): 0.67-1.01, p=0.066]. HIV disclosure rates did not differ across the two study arms. However, among those women who disclosed, there was a significantly higher level of overall personal satisfaction with the response to disclosure from family and friends among women in the treatment (88%) compared to the control group (62%; p=0.004). The results indicate reductions in the level of depressive symptoms comparable with major depressive disorder (MDD) for HIV-positive pregnant women participating in a group counseling intervention. Although the psychosocial group counseling did not significantly increase disclosure rates, an improvement in the level of personal satisfaction resulting from disclosure was associated with the intervention. This suggests that the counseling sessions have likely reduced the burden of depression and helped clients better manage partner reactions to disclosure. Public agencies and non-governmental organizations working in Tanzania and similar settings should consider offering structured psychosocial support groups to HIV-positive pregnant women to prevent poor mental health outcomes, promote early childhood development, and potentially impact HIV-related disease outcomes in the long term.