This study compared cognitive-behavioral psychotherapy with leuprolide acetate (LA) to cognitive-behavioral psychotherapy with saline injections for 12 months. Five white male pedophiles (M age, 50 years; range, 36-58) volunteered for a two-year study. LA was administered by Depo injection (7 mg initially, then 22.5 mg every 3 mos) for 12 months, followed by saline placebo. Effects of LA on testosterone levels, sexual interest preference by visual reaction time (Abel Assessment), penile tumescence (Monarch PPG), as well strong urges and masturbatory frequency to children (polygraph), were measured every three months. Subjects were treated with weekly cognitive-behavioral psychotherapy. On LA, testosterone decreased to castrate levels. Because of the suppression of testosterone, physiologic arousal response as measured by penile plethysmography (penile tumescence) was significantly suppressed compared with baseline. However, sufficient response remained to detect pedophilic interest. This pedophilic interest was also detected by visual reaction times. All subjects self-reported a decrease in strong pedophilic urges and masturbation. When asked about having pedophilic urges and masturbating to thoughts of children, polygraph responses indicated subjects were not deceptive when they reported decreases. On placebo, testosterone and physiologic arousal eventually rose to baseline levels. At baseline and on placebo, subjects were consistently deceptive regarding increased pedophilic urges and masturbatory frequency as noted by polygraph. Interest preference, as measured by Abel Assessment and Monarch PPG, was generally unchanged throughout the study. Cognitive-behavioral psychotherapy augmented with LA significantly reduced pedophilic fantasies, urges, and masturbation, but did not change pedophilic interest during one year of therapy. Deceptive responses by polygraph suggested that self-report was unreliable. Follow-up utilizing objective measures is essential for monitoring efficacy of treatment in pedophilia. Our study supports the supposition that modification of pedophilic behavior is possible. LA may augment cognitive-behavioral psychotherapy and help break the sequence leading to a reoffense.