One to three percent of children and adolescents have Obsessive compulsive disorder (OCD). Although high co-morbidity occurs between OCD and Bipolar Disorder (BD) in adults, there has been limited research on anxiety in pediatric BD. A 15 year-old adolescent on chlorpromazine treatment for OCD was referred for his manic symptoms. During hospitalization, chlorpromazine was discontinued. Lithium 20 mg/kg was initiated gradually. Manic symptoms were recovered in one month. Aripiprazole and clonazepam treatment was combined with cognitive behavioral therapy for his OCD symptoms. He was discharged after 2 months with partial remission of OCD symptoms. This OCD case will be discussed as a severe case with comorbid BD having complicated treatment approach.