Data for the study derive from evaluation of court records of cases against 936 sex offenders in Hamburg from 1964 to 1971. Characteristics of the offenses, the offenders, and the 317 written expert opinions submitted in the cases are considered. Results indicate that about a third of all sex offenders are evaluated by psychiatrists. Written opinions tend to be limited. In the worst cases, the offender is not even interviewed; most offenders are given no physical examination, and no psychological diagnosis is prepared. Sexual anamnesis is wanting in over half the cases, and the opinions in half the cases reflect a negative attitude toward sexuality. Half of the experts identify with the State's power to punish, and 78 percent of the opinions are dominated by narrow biological conceptions of criminality that contribute little to individual assessment of offenders. The quality of the opinions varies widely, with those of the court medical services exhibiting the greatest deficiencies. Clear criteria for requiring an expert opinion do not seem to exist, although evaluated offenders suffer from more somatic illness and have longer records than offenders not evaluated. It is concluded that forensic psychiatric experts do overidentify with the authorities prosecuting criminal offenses. However, as the opinions of the medical court services do not hold up under critical evaluation in 80 percent of the cases, expert opinions should not be sought from this source. Furthermore, the practice of obtaining psychiatric opinions from clinics must be rethought. If clinics are to supply opinions, special training must be provided for experts, as well as for prosecutors and judges, so that concerned parties understand the basic scientific findings about sexual behavior. Finally, research on therapy options for sex offenders must play a role in the controversy surrounding expert psychiatric opinions on sexual offenders, which has not been the case until now. An extensive bibliography (139 entries) and tables are supplied.