Experience with more than 375 cases of possible sexual abuse has taught us that much work still needs to be done in understanding normal prepubertal female anatomy and interpreting findings in sexual abuse cases. Because pediatric clinicians are often called upon to assess possible sexual abuse victims, knowledge of what is known and how best to examine the genitalia of a young girl is essential. Two cases are discussed that involve normal and abnormal anatomy. Examination techniques for adequate visualization include proper tension and timing with the spreading of the labia in the supine position, the knee-chest position, and lateral traction on the buttocks while lying flat on the abdomen to look for anal relaxation. The hymen, contrary to common notion, is often a slack, thick, folded, stretchable tissue which may persist after digital or penile penetration. Findings secondary to sexual abuse are often subtle. Acute tears or bruising are rare because force is seldom a part of the sexual acts committed against a child. A vaginal opening of greater than 5 mm is not common and may indicate vaginal penetration with a finger, object, or penis. An "intact" hymen does not necessarily preclude vaginal penetration. Lack of physical evidence never rules out abuse because many sexual acts leave no physical findings.