BACKGROUND: Sexually transmitted infections (STIs) remain common in the United States. One contributor to this persistent problem is pockets of infection among persons who may not have regular access to health care, a group that includes those who seek services at shelters. OBJECTIVE: The goals of the study were to: 1) determine the acceptability of STI testing among individuals seeking services at shelters in 2 midsized southeastern cities; 2) evaluate the prevalence of chlamydia, gonorrhea, syphilis, and HIV among these individuals; and 3) assess the proportion that subsequently learned their test results and received timely and appropriate treatment if warranted. STUDY DESIGN: Using a cross-sectional design, 430 individuals between the ages of 19 and 45 seen at 3 shelters in 2 cities were approached for participation. After completing a brief behavioral assessment, each participant provided a urine specimen for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) testing, blood for syphilis serologic testing, and an oral sample for HIV testing. RESULTS: The overall recruitment rate was 97% (96% in city A and 98% in city B). Seventy-eight percent were black with a mean age of 35.1 years. STI prevalence among those reporting sexual activity in the past 2 months was 12.9% in city A and 19.9% in city B (P = 0.04). The rate of CT in city B was significantly higher than city A (15.0% vs. 6.4%, P = 0.02); however, similar rates were found for GC (5.0% vs. 3.2%), primary and secondary syphilis (0.08% vs. 1.4%), and HIV (0.07% vs. 0.06%). Overall, 91.5% of the positive cases (89.0% in city A and 94.0% in city B) learned their test results and were successfully treated. CONCLUSION: We found that shelter clients were receptive to STI testing, even for HIV, with most positive cases notified and successfully treated. © Copyright 2006 American Sexually Transmitted Diseases Association.