Objective: To determine the event-level associations between perceived risk of sexually transmitted disease (STD) acquisition/transmission and condom use during penile-vaginal intercourse (PVI) among STD clinic attendees. Method: A convenience sample (N = 622) completed daily electronic assessments. Two questions were proxies of perceived risk: suspicion that the partner might currently have an STD and that "you" might currently have an STD. Participants reported whether condoms were used with PVI events in the past 24 hours. Generalized estimating equations determined the association between each of the perceived risk variables and event-level condom use. Results: For the model pertaining to suspicion of sex partner infection, there were 16,674 events of PVI, with condom use during 10,552 of these events. The effect of current suspicion was significant after adjusting for gender and whether participants identified as African American/Black (estimated odds ratio = 2.17, 95% confidence interval = 1.57-3.00, P = 0.0001). The model pertaining to suspicion of self-infection included 16,679 events of penile-vaginal sex, with condom use during 10,557 of these events. Again, the effect of current suspicion was significant after adjusting for gender and African American/Black race (estimated odds ratio = 2.05, 95% confidence interval = 1.43-2.40, P = 0.0001). Tests for interactions with gender and with race were nonsignificant (all Ps > 0.25). Conclusion: Using an event-level research design, strong associations were found between perceptions of STD risk and condom use in a clinical population. Health care providers and other professionals may indirectly promote condom use by helping clinic patients realistically evaluate their risk of having sex with infected partners or of being a source of STD transmission to others.