BACKGROUND AND OBJECTIVES: Information available on HIV-2 and dual infection (HIV-1/2) is limited. This study was carried out among HIV positive individuals in an urban referral clinic in Khar, Mumbai, India, to report on relative proportions of HIV-1, HIV-2 and HIV-1/2 and baseline characteristics, response to and outcomes on antiretroviral treatment (ART). METHODS: Retrospective analysis of programme data (May 2006-May 2009) at Khar HIV/AIDS clinic at Mumbai, India was done. Three test algorithm was used to diagnose HIV-1 and -2 infection. Standard ART was given to infected individuals. Information was collected on standardized forms. RESULTS: A total of 524 individuals (male=51%; median age=37 yr) were included in the analysis over a 3 year period (2006-2009) - 489 (93%) with HIV-1, 28 (6%) with HIV-2 and 7(1%) with dual HIV-1/2 infection. HIV-2 individuals were significantly older than HIV-1 individuals (P<0.001). A significantly higher proportion of HIV-2 patients and those with dual infections had CD4 counts <200 cells/μl compared to HIV-1. HIV-2 individuals were more likely to present in WHO Clinical Stage 4. Of the 443 patients who were started on ART, 358 (81%) were still alive and on ART, 38 (8.5%) died and 3 were transferred out. CD4 count recovery at 6 and 12 months was satisfactory for HIV-1 and HIV-2 patients on protease inhibitor based regimens while this was significantly lower in HIV-2 individuals receiving 3 nucleoside reverse transcriptase inhibitors. INTERPRETATION AND CONCLUSIONS: In an urban HIV clinic in Mumbai, India, HIV-2 and dual infections are not uncommon. Adaptation of the current national diagnostic and management protocols to include discriminatory testing for HIV types and providing access to appropriate and effective ART regimens will prevent the development of viral resistance and preserve future therapeutic options.