The role of the police surgeon in the investigation of sex offenses is crucial in gaining victim cooperation and providing the physical evidence for prosecution. Victim consent to a medical examination is required. Without being coercive, the police surgeon should indicate to resistant victims that refusal to submit to an examination seriously hinders the investigation. If possible, the victim should be allowed to set conditions for the examination, such as the surroundings, the people who will be present, and examination by a female doctor. When dealing with child victims, permission for the examination should be obtained from parents or guardians and preferably from the child as well. A policewoman should be present at the examination to act as a witness and assist with the collection of evidence. Although the primary duty of the police surgeon is to obtain evidence for the prosecuting attorney, the treatment of victim injuries should also have priority. This does not include followup treatment, which should be done by the victim's own physician. Examination of an accused sex offender poses various legal problems, given the rights accorded an accused. The police surgeon can at least perform a visual examination of the accused to ascertain any visible signs of injury or struggle. The discussion briefly considers the investigatory aspects of crimes associated with homosexuality and prostitution. Sixteen selected readings are listed.