Interest in the treatment of pediatric obsessive-compulsive disorder (OCD) has increased as our knowledge of adult OCD has expanded. Although adults are still the majority of patients, children and adolescents with OCD are being identified and treated more frequently. As this population is better identified, prognostic factors need to be addressed to improve treatment outcome. The purpose of this study was to determine the role of family psychiatric pathology in fluvoxamine treatment outcome. Eleven children and adolescents with OCD and one of their parents participated in the study. Four parents were diagnosed with OCD, six had an Axis I diagnosis other than OCD, and one had no mental disorder [Structured Clinical Interview for the DSM-Non-Patient edition (SCID-NP)]. Each patient received fluvoxamine for 58 weeks. Dependent measures included the Children Yale-Brown Obsessive Compulsive Scale (CY-BOCS), the NIMH-Global Obsessive Compulsive Scale (NIMH-GOCS) and the Clinical Global Impression (CGI). Based on CY-BOCS, CGI and NIMH-GOCS scores, patients with parents who have OCD showed a clinically and statistically significant reduction in symptoms from pre- to post-treatment. Patients whose parents did not have OCD also improved. However, the improvement was statistically but not clinically significant. The presence of OCD in one parent seems to modify a child's response to medication. The results suggest that family psychopathology, specifically presence of OCD, may contribute to treatment efficacy. Further research is suggested in this area.