Objectives. To examine gaps in identification of preexposure prophylaxis (PrEP) candidates, uptake, and use of PrEP by populations most likely to seroconvert.Methods. At a federally qualified health center in Chicago, Illinois, we used electronic medical records, prescription data, and our best approximation of Centers for Disease Control and Prevention PrEP guidelines to determine how many patients were indicated for PrEP relative to HIV diagnoses (indication:HIV), how many were on PrEP relative to indications (PrEP:indication), and how many were on PrEP relative to HIV diagnoses (PrEP:HIV). We compared these ratios across age, gender and orientation, race/ethnicity, and insurance.Results. Overall, there were 32 indications per incident diagnosis and 16 patients on PrEP per incident diagnosis. In adjusted models, Whites had higher indication:HIV and PrEP:HIV ratios compared with Blacks, men who have sex with men had higher indication:HIV and PrEP:HIV ratios compared with transwomen but lower PrEP:indication ratios, and uninsured patients had higher indication:HIV but lower PrEP:indication and PrEP:HIV ratios compared with those with insurance.Conclusions. PrEP use, relative to HIV diagnoses, differs by important patient characteristics. While improved guidelines will address some of the disparity, better approaches for determining PrEP candidates and more normalized patient-provider communication are needed to ensure better PrEP access to all individuals at high risk for HIV.