HIV-positive men who have sex with men (MSM) were recruited on www.Facebook.com and www.Poz.com to give HIV self-tests to their contacts. Study participants completed a baseline survey, were given two self-tests, and completed a survey 2 months later. Of 133 eligible men, 40 (30%) completed both surveys. Most participants were 30-54 years old and non-Hispanic white. Some had a detectable viral load (n = 4), had condomless anal sex with male partners of negative or unknown status (n = 17), and had met anal sex partners at gay dating websites (n = 23). Of 80 self-tests given to participants, 59 (74%) were distributed, primarily to non-Hispanic white MSM, 30-54 years old who were friends. Participants reported results from 31 distributed tests; 2 sex partners of participants had positive results. Participants indicated these two persons were unaware of their infections. Expanding recruitment websites might reach non-white MSM. Unrecognized infections were identified through online recruitment and self-test distribution via HIV-positive persons.