Objective:To evaluate the prevalence of asymptomaticChlamydia trachomatisgenitourinary infection in women with human immunodeficiency virus (HIV) infection.Methods:The prevalence of asymptomatic chlamydial genitourinary infection in HIV‐seropositive women was compared with both HIV‐seronegative controls and women with unknown HIV status.Chlamydia trachomatiswas isolated in cell culture from endocervical and urethral specimens.Results:The prevalence of genitourinaryC trachomatisinfection among HIV‐seropositive women was 18.3% (21 of 115), a rate significantly higher than in both HIV‐negative women (11 of 136;P= .016) and controls with unknown HIV status (18 of 326;P= .0001). Crude odds ratios for endocervical and urethral chlamydial infection in HIV‐seropositive women compared to HIV‐seronegative controls were 2.6 (95% confidence interval [CI] 1.13‐6.08) and 3.3 (95% CI 1.15‐9.67), respectively. After adjustment for variables related to sexual habits, there was no difference in the risk of cervicalC trachomatisinfection between HIV‐seropositive cases and HIV‐seronegative controls (Mantel‐Haenszel odds ratio 1.04, 95% CI 0.93‐1.14;P= .41). Finally, in HIV‐seropositive patients, both the severity of immunosuppression evaluated by CD4+, CD8+, and total lymphocyte counts and the detection of p24 HIV‐related antigen did not correlate with the presence of chlamydial infection.Conclusions:Women infected with HIV are at high risk for asymptomatic genitourinary chlamydial colonization. To prevent a possible “epidemic” of pelvic inflammatory disease, appropriate screening programs and therapeutic strategies should be planned.(Obstet Gynecol 1994;83:1005‐10)