People living with HIV (PLWH) engaged in medical care represent an accessible group to focus HIV prevention efforts. In an analysis of 1,883 PLWH from 2007 and 2015, we determined the proportion at risk of HIV transmission and identified factors associated with HIV transmission risk using multivariable mixed effects logistic regression models with random intercepts. HIV transmission risk was defined by an HIV viral load > 1,500 copies/mL and self-reported unprotected sex. We found that 174 (9.2%) individuals were at risk for HIV transmission at least once. Factors associated with HIV transmission risk included younger age (adjusted OR [95% CI] per decade decrease = 2.30 [1.84, 2.89]), illicit drug use (adjusted OR = 5.36 [3.02, 9.56]), depression (adjusted OR = 1.88 [1.10, 3.21]), and education <12th grade (adjusted OR = 2.05 [1.15, 3.67]). Thus, nearly 1 in 10 HIV-infected individuals engaged in care between 2007 and 2015 were potentially at risk of transmitting HIV. Behavioral interventions to decrease HIV transmission should focus on younger, less educated patients who are depressed and actively using illicit drugs.