Overall, 50.6 percent of the men expressed a desire for treatment, 42 percent attended treatment, and 13.6 percent completed at least one course of some type of treatment. Historical trends over the study period showed a decline in male sex offenders' expressed wish for treatment, and correspondingly fewer offenders participated in or completed treatment. The 1980s marked the beginning of this decline. The authors discuss why this decline may have been linked to Canadian reporting laws that require mental health professionals to report any child who has been physically or sexually abused, which removed the legal protection of the therapist-client privilege. Those who denied responsibility for their offense and those who denied having a sexual disorder were less likely to want treatment or to be in any treatment program. Age, marital status, and education had little impact on treatment acceptance and compliance. Exhibitionists most often expressed a desire for treatment, but did not differ from other groups in treatment completion. Higher treatment attrition rates were found for offenders with learning problems, antisocial personality disorders, and psychopaths. The sample was selected from a forensic database. All the men received a psychological assessment at a major metropolitan university hospital from 1966 to 1991 and at a private clinic from 1991 to 2003. Their medical and psychological files were examined by 6 raters who collectively scored more than 500 variables for each offender. Participation in treatment and treatment completion was based on hospital records and discharge information. The desire for treatment at the time of assessment was determined by responses to questions by the examining clinician. 4 tables and 36 references