HIV RNA levels are usually high early in HIV infection. In the HPTN 061 study, men were tested for HIV infection every six months; six (21.4%) of 28 men who acquired HIV infection during the study had low or undetectable HIV RNA at the time of HIV diagnosis. Antiretroviral drugs were not detected at the time of HIV diagnosis. False-negative HIV test results were obtained for two men using multiple assays. Antiretroviral drug resistance mutations were detected in HIV from one man. Additional studies are needed to identify factors associated with low HIV RNA levels during early HIV infection.