A questionnaire was designed to assess perceptions of clinicians who administered in-prison sex offender treatment programs in Taiwan and Michigan. Clinicians were asked about types of sex offenders they treated and their perceptions of the degree of difficulty in treating these sex offenders. The Groth typology of sex offenders was used as the baseline typology. The final sample included 34 clinicians in Taiwan and 33 clinicians in Michigan. Results showed significant differences in the proportion of rapists and child molesters between Taiwan and Michigan, but no significant differences were found in other types of sex offenders. Rankings by clinicians on the degree of difficulty in treating different types of sex offenders were identical in both countries, although clinical experiences of clinicians were different. Clinicians in both countries believed that sadistic rapists and fixated child molesters were the most difficult types of sex offenders to treat. 15 references, 3 notes, and 4 tables