Poor insight has been reported in 15% to 36% of patients with obsessive-compulsive disorder (OCD), but little is known about its clinical correlations. This study examines insight among patients with OCD using a standardized instrument, the Brown Assessment of Beliefs Scale, and analyzes its relationship with clinical factors. Insight was assessed in 132 patients with OCD, before and after pharmacologic treatment, using the Brown Assessment of Beliefs Scale. Differences between patients with good and poor insight on sociodemographic variables, OCD severity, comorbidity, and treatment response were studied. Stability of insight after pharmacologic treatment was also examined. Thirty-nine patients (29.5%) exhibited poor insight. They showed more depressive symptoms (P = .001) and personality disorders (P = .001), especially the schizotypal form, than did good insight subjects, but there were no significant differences in treatment response. Insight significantly improves after treatment (P < .001). Our results suggest that insight in OCD varies widely and constitutes a dynamic phenomenon that can improve after treatment and is influenced by clinical conditions such as affective status or personality.