Pre-Exposure Prophylaxis (PrEP) is a priority method for preventing HIV infection. This study's aims were threefold: (1) identify characteristics of members of a large health maintenance organization, Kaiser Permanente Georgia (KPGA), associated with HIV infection, (2) identify which member characteristics associated with HIV were also associated with PrEP prescription, and (3) identify which HIV-associated characteristics were associated with under- or over-prescribing of PrEP. Analysis of variables from the electronic medical record revealed that age, race, gender, mental health diagnosis, STI diagnosis, and sexual orientation were independently associated with HIV diagnosis. The same characteristics were independently associated with PrEP prescription except for race. Persons identifying as Black or unknown race, women, and/or heterosexual; and who had an STI diagnosis and/or illicit drug use had lower odds of being prescribed PrEP than of having an HIV diagnosis. The implications of these findings for improving physician identification of candidates for PrEP prescription are discussed.