This study investigated the presence of obsessive-compulsive personality disorder (OCPD) in a group of 277 patients (88 with obsessive-compulsive disorder [OCD], 58 with major depressive disorder [MDD], and 131 with panic disorder [Panic]) to test the specificity of the relationship between OCPD and OCD. OCPD is statistically significantly more frequent in patients with OCD than in those with Panic and MDD. The distribution of single criteria of OCPD in the three groups does not differ significantly. Discriminant analysis selects a list of items that provide a correct classification rate of 66% based on OCPD criteria selected by canonical function. OCD patients with and without OCPD do not differ in sex, age of onset, duration of illness, positive family history for Tics disorder/Tourette syndrome (TS), or morbidity risk for OCD.