HIV testing can decrease risky sexual behavior among HIV-positive men who have sex with men (MSM) and provide a gateway into HIV/AIDS care and treatment. MSM in South Africa, however, do not currently utilize clinic-based HIV testing at a rate commensurate with their risk and too few know their status. In South Africa programs have largely failed to engage Men who have Sex with Men (MSM): a population with an extremely high burden of disease and high rates undiagnosed HIV infections. Recent bio-behavioral surveillance data undertaken by this investigative team in Mpumalanga Province demonstrated prevalence among MSM at above 30%, with 54% of HIV positive MSM unaware of their status prior to survey participation. Urgently needed strategies to expand HIV testing among MSM in South Africa may include new HIV self-testing kits that offer an alternative to clinic-based testing. Self-tests expand testing beyond the clinic, which is of particular significance for MSM and other key populations who require more frequent testing and are less comfortable accessing clinic services. While self-conducted HIV tests could expand the package of testing options in South Africa, thus facilitating earlier HIV detection and treatment, there isa lack of information regarding acceptability, feasibility, or potential behavioral impacts of introducing the HIV self-test among African MSM. To address this gap, we propose to determine the acceptability (Aim 1), the feasibility (Aim 2) and the behavioral impacts (aim 3) of HIV self-testing among South African MSM currently enrolled in NIH-sponsored cohorts (R01AI092892, Lane). We will explore whether self-testing will be used by South African MSM; how, when, where, what kind, and with whom self-tests are utilized; how sexual risk behaviors may be modified by introducing self-test kits into this community; and strategies to ensure linkage to care following self-testing in this underserved and high risk population. We will achieve these aims by first conducting a pre-pilot study to explore initial acceptability of both blood-based and oral fluid self-tests and to understand what is necessary to ensure safe and correct usage of both self-tests in a controlled environment. We will then conduct a pilot study, where we will distribute self-testing kits to HIV-negative MSM and follow their use over the course of 6 months. We will implement this study among MSM participating in cohorts recruited from the high prevalence Gert Sibande and Ehlanzeni districts. This proposal offers a unique opportunity to explore self-testing among MSM within established NIH-supported cohorts where a productive research partnership is already underway. The proposed research will provide information critical to understanding how self-tests would fit into a package of expanded testing options for high risk communities experiencing barriers to clinic-based testing and support future research to determine whether introduction of self-testing can improve early detection and entry to care and facilitate safer sexual behaviors, thus leading to prevention gains.