This study sought to identify the magnitude of HIV risk in a diverse sample of Men who use the Internet to seek Sex with Men (MISM), and test if specific subpopulations are at sufficiently increased risk to warrant tailored interventions. A sample of 2,716 American MISM, stratified by race/ethnicity, completed an Internet survey of online and offline sex seeking behavior during the last 3 months. Across most demographics, a minority of MISM reported unprotected anal intercourse with male partners (UAIMP). Across all demographics, risk of UAIMP substantially increased with partners met online. Other predictors of increased online partner risk include being 30-39 years old, having children, not living in the Northeast, and low income. HIV-positive men and African Americans reported increased online and offline partner risk. To address higher risk of UAIMP, online HIV interventions should prioritize the needs of MISM, especially HIV-positive men, with content focused on online-mediated liaisons.