OBJECTIVE: Compulsive hoarding and saving symptoms, found in many patients with obsessive-compulsive disorder (OCD), are part of a discrete clinical syndrome that includes indecisiveness, disorganization, perfectionism, procrastination, and avoidance and has been associated with poor response to medications and cognitive behavior therapy. The authors sought to identify cerebral metabolic patterns specifically associated with the compulsive hoarding syndrome using positron emission tomography (PET). METHOD: [(18)F]Fluorodeoxyglucose PET scans were obtained for 45 adult subjects who met DSM-IV criteria for OCD (12 of whom had compulsive hoarding as their most prominent OCD symptom factor) and 17 normal comparison subjects. All subjects had been free of psychotropic medication for at least 4 weeks. Regional cerebral glucose metabolism was compared between the groups. RESULTS: In relation to the comparison subjects, the patients with compulsive hoarding syndrome had significantly lower glucose metabolism in the posterior cingulate gyrus and cuneus, whereas the nonhoarding OCD patients had significantly higher glucose metabolism in the bilateral thalamus and caudate. In relation to nonhoarding OCD patients, compulsive hoarders had significantly lower metabolism in the dorsal anterior cingulate gyrus. Across all OCD patients, hoarding severity was negatively correlated with glucose metabolism in the dorsal anterior cingulate gyrus. CONCLUSIONS: OCD patients with the compulsive hoarding syndrome had a different pattern of cerebral glucose metabolism than nonhoarding OCD patients and comparison subjects. Obsessive-compulsive hoarding may be a neurobiologically distinct subgroup or variant of OCD whose symptoms and poor response to anti-obsessional treatment are mediated by lower activity in the cingulate cortex.