African Americans are disproportionately infected with HIV/AIDS. Despite Centers for Disease Control and Prevention (CDC) guidelines recommending routine opt-out testing for HIV, most HIV screening is based on self-perceived HIV risks. Philadelphia launched a rapid HIV testing program in seven public health clinics in 2007. The program provides free rapid oral HIV tests to all patients presenting for health services who provide informed consent. We analyzed demographic, risk behavior, and HIV serostatus data collected during the program between September 2007 and January 2009. We used multivariable logistic regression to estimate the association between behavioral and demographic factors and newly diagnosed HIV infection. Of the 5871 individuals testing for HIV, 47% were male, 88% were African American, and the mean age was 34.7 years. Overall HIV prevalence was 1.1%. All positive tests represented new HIV diagnoses, and 72% of individuals reported testing previously. Approximately 90% of HIV-positive individuals and 92% of individuals with more than five recent sex partners never, or only sometimes, used condoms. Two thirds of individuals testing positive and 87% of individuals testing negative assessed their own HIV risk as zero or low. Individuals reporting cocaine use and ever having a same sex partner both had 2.6 times greater odds of testing positive. Condom use in this population was low, even among high-risk individuals. Philadelphia's program successfully provided HIV testing to many underserved African Americans who underestimate their HIV risk. Our results nevertheless suggest greater efforts are needed to encourage more individuals to undergo HIV testing in Philadelphia, particularly those who have never tested.