OBJECTIVE: The objective of this study was to describe the epidemiology of Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, Treponema pallidum, HIV, and herpes simplex virus type 2 (HSV-2) infection diagnosed by culture or by serologic or microscopic tests and by nucleic acid amplification tests in children who are evaluated for sexual victimization. METHODS: Children aged 0 to 13 years, evaluated for sexual victimization, who required sexually transmissible infection (STI) testing were enrolled at 4 US tertiary referral centers. Specimens for N gonorrhoeae and C trachomatis cultures, wet mounts for detection of T vaginalis, and serologic tests for syphilis and HIV were collected and processed according to study sites' protocols. Nucleic acid amplification tests for C trachomatis and N gonorrhoeae and serologic tests for HSV-2 were performed blinded to other data. RESULTS: Of 536 children enrolled, 485 were female. C trachomatis was detected in 15 (3.1%) and N gonorrhoeae in 16 (3.3%) girls. T vaginalis was identified in 5 (5.9%) of 85 girls by wet mount, 1 (0.3%) of 384 children had a positive serologic screen for syphilis, and 0 of 384 had serologic evidence of HIV infection. Of 12 girls who had a specimen for HSV-2 culture, 5 (41.7%) had a positive result; 7 (2.5%) of 283 had antibody evidence of HSV-2 infection. Overall, 40 (8.2%) of 485 girls and 0 of 51 boys (P = .02) had >or=1 STI. Girls with vaginal discharge were more likely to test positive for an STI (13 [24.5%] of 53) than other girls (27 [6.3%] of 432; prevalence ratio = 3.9; P < .001), although 10 girls with STIs had normal physical examinations. Most girls (27 [67.5%]) with a confirmed STI had normal or nonspecific findings on anogenital examination. CONCLUSIONS: The prevalence of each STI among sexually victimized children is <10%, even when highly sensitive detection methods are used. Most children with STIs have normal or nonspecific findings on physical examination.