Background: To investigate the prevalence and correlations of suicidal behavior in obsessive compulsive disorder (OCD) among adolescent psychiatric inpatients. Methods: A total of 348 adolescents, representing consecutive admissions to an adolescent inpatient unit, were assessed. Of these, 40 patients had OCD, 118 had schizophrenia, 59 had an affective disorder, 81 had a conduct disorder and 50 had an eating disorder. In addition, 87 normal community controls were assessed. All subjects were assessed for suicidal behavior by the Childhood Suicide Potential Scale (CSPS), for depression by the Beck Depression Inventory, for impulsiveness by the Impulse Control Scale, for anxiety by the State-Trait Anxiety Scale and for aggression by the Yudowsky Overt Aggression Scale. Results: All the psychiatrically ill subjects, including those with OCD, had high levels of depression, anxiety and impulsiveness, which were far higher than those of the controls. The rate of attempted suicide was, however, much lower in the OCD subjects. In addition, there was a significant inverse correlation between suicidal behavior levels on the CSPS and depression in the OCD subjects, while all other subjects showed the expected significant positive correlation between level of suicidal behavior and depression. Limitations: This study looked at a referred population and generalization to outpatient and community samples cannot be made. Distinguishing between the primary and the comorbid diagnosis is difficult and some findings are based on small sample size and therefore may be vulnerable to type I error. Conclusions: Although suicidal ideation and depressive symptoms are common in OCD adolescent inpatients, they seem to be protected against suicide attempts. The inverse relationship between suicidal behavior and depression may mean that suicidal behavior is, in some ways, qualitatively different from that seen in other psychiatrically ill adolescents.