Despite advances in our understanding of the pathology and genetics of obsessive compulsive disorder (OCD) and in our ability to successfully treat patients with medications and behavioral psychotherapy, the identification of homogeneous subgroups of patients with OCD has remained elusive. Once identified, such subgroups may be found related to treatment response, biological markers, or genetic transmission of OCD. To clarify identification of symptom subtypes, my colleagues and I administered the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Symptom Checklist to 107 patients with OCD and applied principal components analysis (e.g., factor analysis) to these data. We then examined the correlations between these factor scores and the presence of comorbid tic and personality disorders, which are thought to be related to OCD. We found that three factors, which we named "symmetry/hoarding," "contamination/cleaning," and "pure obsessions," best explained the symptoms of the Y-BOCS Symptom Checklist. Only the first factor was significantly related to comorbid obsessive compulsive personality disorder or to a lifetime history of Tourette's syndrome or chronic tic disorder. Implications of these findings regarding possible clinical utility are discussed.