Because urogenital trauma frequently raises the question of sexual abuse, it is important to be able to relate the mechanism of injury to expected examination findings. This study was undertaken to characterize the trauma that results from straddling and correlate such injuries with the history, examination, and patient characteristics. The charts of 100 patients examined in an urban pediatric emergency department were reviewed; their conditions met the criteria of straddle injury--a blow to the perineum as a result of falling or striking a surface or an object with the force of one's own body weight. Ages ranged from 9 to 187 months (mean, 77.9; median, 67.2); 72% were female. Most injuries were minor lacerations and abrasions of the genitalia. Eleven percent had injury to the posterior fourchette. Hymenal and vaginal injuries were primarily caused by penetrating mechanisms. Five patients who presented with a history of straddling subsequently received the diagnosis of sexual assault based on disclosure by the patient or a witness and inconsistency of physical findings. There were no urethral or perianal injuries resulting from nonpenetrating straddle mechanisms. Straddle injuries include a variety of mostly minor urogenital injuries. Perianal, hymenal, or vaginal trauma suggests a penetrating mechanism, either unintentional or from sexual assault. An investigation for sexual assault should be initiated in the following cases: infants younger than 9 months of age; perianal, hymenal, or vaginal injury; extensive or severe injury; concurrent nonurogenital injuries; and whenever there is lack of correlation between history and physical findings.