The suitability and accuracy of using simple human immunodeficiency virus (HIV) rapid (SR) tests in community-based clinics in northwest Tanzania were determined to assess eligibility for participation in clinical trials. The HIV rapid and ELISA test results for 789 women aged 16 to 54 who were screened for two clinical trials of HIV prevention were compared. Women were offered voluntary HIV counseling and testing (VCT) at screening; those who accepted were tested with the Abbott Determine and Trinity Biotech Capillus SR tests in parallel. The results were confirmed by two parallel HIV enzyme-linked immunosorbent assay (ELISA) tests (Abbott Murex HIV Ag/Ab combination and Vironostika Uniform II HIV Ag/Ab) to determine eligibility. Positive samples for any of the four assays were confirmed by a line immunoassay and p24 testing. The parallel SR tests had high concordance (96.2%) with the parallel ELISA algorithm. The sensitivities of the SR tests were 98.6% for Capillus (95% confidence interval [CI], 95.1 to 99.8%), 99.3% for Determine (95% CI, 96.2 to 100%), and 98.6% for the parallel SR (95% CI, 95.1 to 99.8%). The specificities were 99.7% for Capillus (95% CI, 98.9 to 100%), 99.7% for Determine (95% CI, 98.9 to 100%), and 100% for the parallel SR (95% CI, 99.4 to 100%). SR tests are suitable for use in community-based clinical research settings to assess eligibility both for trial participation and for the provision of on-site VCT services.