The purpose of this study was to describe and analyze the characteristics of, and the clinical correlates to, concave hymenal variations in a large number of suspected child sexual abuse victims. Thirteen hundred eighty-three female child and adolescent suspected sexual abuse victims were comprehensively evaluated. Photocolposcopy was used for the anogenital examinations. Concave hymenal variations were found in 174 patients (12.6%). Sixty-one (35.1%) were anterior. Of these, 40 (65.6%) were curved and smooth, and 21 (34.4%) were angular and/or irregular. One hundred (57.5%) were posterior/lateral. Of these, 33 (33%) were curved and smooth, and 67 (67%) were angular and/or irregular. Thirteen patients (7.5%) had multiple hymenal concavities. Posterior/lateral location was associated with penile-vaginal contact (P = .004), penetration (P = .006), stranger perpetrator (P = .032), hymenal rim narrowing (P less than .001), and posterior fourchette abnormality (P = .049). Angular and/or irregular features were associated with penile contact (P = .005), vaginal contact (P = .035), penile-vaginal contact specifically (P less than .001), penetration (P = .046), abnormal general physical examination (P = .018), and hymenal rim narrowing (P less than .001). Logistic regression analysis demonstrated that age-specific prevalence trends for posterior/lateral (P less than .001) and angular and/or irregular (P = .011) concavities were consistent with acquired anatomic findings. An interobserver exercise with five "blinded" raters evaluating photographs of 49 patients showed significant agreement among observers in sorting posterior/lateral and angular concavities into the diagnostic categories "suggestive of trauma" and "trauma."(ABSTRACT TRUNCATED AT 250 WORDS)