The goal of this study is comparing efficacy of Omega-3 and placebo in reducing depression beck score in HIV/AIDS patients. This study is a randomized, double-blind clinical trial. One-hundred HIV positive patients, received antiretroviral therapy for at least one year and CD4 count≥350, with beck depression score≥16 will be included. Based on the block randomization method, included patients will be recruited in two equal groups. First group will be received soft gelatin Cap of omega-3, 1000 mg twice daily, for 8 weeks. The second group will be received placebo Cap, 1000 mg twice daily, for 8 weeks. Patients with history of other psychological disorders, major depression with recent suicidal attempt, history of drugs or alcohol abuse, sensitivity to omega-3, coagulation disorders or intake of anticoagulants and receiving any drugs that affect patients’ mood including anti-depressants will be excluded. The patients will be visited at time of entrance to the study and weeks 4 and 8. All patients will complete beck depression questionnaire at these times. Finally changes in the beck depression scores will be compared between the groups.