Obsessive-compulsive symptoms among youth with Prader-Willi Syndrome (PWS) are frequently present and associated with considerable problems in the daily functioning of the child and his/her family. Although pharmacological and psychosocial treatments exist that target obsessive-compulsive symptoms among typically developing youth, these treatments have not been systematically adapted and/or evaluated for this population. Furthermore, although psychotropic medications have shown promising support in addressing obsessive-compulsive symptoms in several case reports involving youth with PWS, associated efficacy is modest and potential for side effects is a realistic concern. Given efficacy and tolerability of cognitive-behavioral treatment for obsessive-compulsive symptoms in typically developing youth, an adapted version of this approach may hold promise in treating clinically problematic obsessive-compulsive symptoms in youth with PWS. Thus, we report on a case series of behavioral treatment for obsessive-compulsive symptoms in three youth with PWS. Diagnostic and symptom severity assessments were conducted at screening, pre-treatment, and post-treatment by a trained independent evaluator. All youth were considered treatment responders and exhibited meaningful reductions in compulsion severity, overall obsessivecompulsive severity, and obsessive-compulsive related impairment. These data provide preliminary evidence for the utility of behavioral therapy in treating obsessive-compulsive symptoms in youth with PWS.