Context: PrEP, available and free of charge in France, is gaining popularity among gbMSM, but is still underused in this at-risk population. Objective: To investigate factors that predict PrEP use among an eligible sample (PrEP users vs. nonusers). Methods: Data was collected through an online questionnaire completed by 10,853 French participants (Net Gay Barometer, 2018). Amongst 8,411 HIV-negative gbMSM and trans people living in France, 3,251 (38.7%) were considered eligible to PrEP according to French guidelines, out of which 445 (13.7%) were already PrEP users. Univariate and multivariate logistic regression were used. Results: Although similar in many aspects to other eligible participants, PrEP users tend to engage in riskier sexual practices with their casual male partners than their non-user counterparts. Our multivariate model accounted for nearly 53% of the variance of the probability to take PrEP when eligible (pseudoR2=0.53). After controlling for their more advantageous sociodemographic profile, it seems that concerns with HIV prevention and a high perceived efficacy of PrEP to protect against HIV are key predictors of PrEP use. Conclusion: The proportion of gbMSM and trans people eligible to PrEP that do not use it is high. In the context where PrEP is free in France and will soon be made accessible through general practitioners, efforts must be made to recommend it to these people. PrEP use appears to be associated with more abundant and diverse sexuality and a higher prevalence of STIs. PrEP follow-up facilitates early detection and prompt treatment of STIs, when treatment is available.