This study investigated lifetime prevalence rates, demographic characteristics, childhood conduct disorder and adult antisocial features, suicide attempts, and cognitive impairment in individuals with obsessive-compulsive disorder (OCD) uncomplicated by or comorbid with any other psychiatric disorder. The data are from the NIMH Epidemiologic Catchment Area (ECA) study, and the current analyses compared subjects with uncomplicated OCD (no history of any other lifetime psychiatric disorder), comorbid OCD (with any other lifetime disorder), other lifetime psychiatric disorders, and no lifetime psychiatric disorders across these variables. OCD in its uncomplicated and comorbid form had significantly higher rates of childhood conduct symptoms, adult antisocial personality disorder problems, and of suicide attempts than did no or other disorders. Comorbid OCD subjects had higher rates of mild cognitive impairment on the Mini-Mental Status Exam than did subjects with other disorders. These findings suggest that a subgroup of OCD patients may have impulsive features, including childhood conduct disorder symptoms and an increased rate of suicide attempts; wider clinical attention to these outcomes is needed.