Rapid HIV testing allows same-day results, increasing the number of persons who learn their HIV status. Understanding how clients in different settings perceive rapid testing may increase acceptance of this technology. From June 1999 to August 2001 we interviewed 256 clients at a publicly funded urban sexually transmitted disease (STD) clinic and 1201 clients at a community- based HIV counseling, testing, and referral center (Los Angeles Gay and Lesbian Center; LAGLC) about their posttest satisfaction with rapid HIV testing. HIV prevalence was 3.9% at the STD clinic and 5.3% at the LAGLC. In multivariate analysis, adjusting for age, sexual orientation, race/ethnicity, history of STDs, self-perceived HIV risk, prior HIV test and HIV testing results, clients at the STD clinics (versus LAGLC) were more likely to find testing stressful (adjusted odds ratio [AOR]: 1.75, 95% confidence limits [CL]: 1.27, 2.42) and feel that they received their results too quickly (AOR: 2.05, 95% CL: 1.39, 3.03). Latinos (versus whites) were more likely to report that they received their results too quickly (AOR: 4.99, 95% CL: 3.48, 7.14) and that it would be better to wait a week for HIV test results (AOR: 2.48, 95% CL: 1.51, 4.09). Further research may elucidate the reasons why some groups prefer to wait for results, and enable policymakers to better design strategies to reach high-risk groups with rapid HIV testing.