Fresh injuries of the anal region concerning infants should always lead to the suspicion of sexual abuse (rape as described in A 176 of the German Penal Code). A differentiation must be made between findings indicative of acute and chronic anal sexual abuse. In clinical forensic medicine such injuries due to acute anal penetration must be documented and an expert opinion must be made. In individual cases a differential diagnosis with respect to an alleged accidental event or to pre-existing diseases must be taken into consideration. To demonstrate the relevant findings and the difficulties arising in the assessment, four cases are presented.