Various schemes have been developed in attempts to define meaningful subtypes of obsessive-compulsive disorder (OCD). A factor analytic approach presumes that the symptom of the disorder can be described by several independent symptom dimensions. The purpose of this study was to explore the neural correlates of three symptom dimensions that were derived from previous factor analyses. Positron emission tomography was used to measure relative regional cerebral blood flow (rCBF) in 14 subjects with OCD while they engaged in a continuous performance task. Clinical indices, including factor scores, we ascertained via structured interviews plus administration of the Yale-Brown Obsessive-Compulsive Scale and checklist. The severity of Factor 1 (religious/aggressive/sexual obsessions and checking) was positively correlated with rCBF in striatum bilaterally. In addition, distinct trends were observed for the other two Factors. These findings provide initial support for a modular neurobiologic model of OCD, where dysfunction within separate component systems may principally mediate independent symptom factors. More important, this nove strategy may represent a powerful new approach to interpreting brain imaging studies of neuropsychiatric diseases.