The present study assessed the presence of post-traumatic stress disorder (PTSD) symptoms in response to stressful or traumatic life events and their impact on HIV risk behaviors and associated psychosocial variables among men who have sex with men (MSM). Participants (n=189; 60% HIV-infected) who were recruited by notices posted in a community health clinic and via a modified respondent-driven sampling technique completed a behavioral assessment survey. Sixty percentage of participants screened positive for having PTSD symptoms using the startle, physiological arousal, anger, and numbness screening instrument. After controlling for race, sexual self-identification, and HIV status, multivariable logistic regression analyses revealed that screening in for having PTSD symptoms was significantly associated with having engaged in unprotected anal (insertive or receptive) sex in the past 12 months, over and above any effects of whether or not a traumatic/stressful event occurred during the year (adjusted odds ratio [OR] = 2.72; p<0.02; 95% confidence interval [CI] = 1.19-6.20). In addition, MSM with PTSD symptoms were more likely to have clinically significant depressive symptoms (adjusted OR = 3.50; p<0.001) and/or symptoms of social anxiety (adjusted OR = 2.87; p<0.01; 95% CI = 1.48-5.62). The current study, in the context of other research documenting the high rates of co-occurring psychosocial issues facing MSM, points to the importance of incorporating coping with these issues in HIV and sexually transmitted disease prevention and care interventions.