Pediatric bipolar disorder (PBD) has a course that is more serious than adult onset bipolar disorder (BD) and has a poorer prognosis. In this paper, two adolescent patients, who had obsessive–compulsive disorder (OCD) and attention deficit/hyperactivity disorder (ADHD) comorbidity and their following diagnosis “BD” are described. These cases were interestingly resistant to the treatment. Case 1: The seventeen-years old patient was brought to our clinic by his father with restlessness, distractibility and nervousness as well as serious obsessions of cleanliness and sanitation. He was diagnosed with OCD and ADHD according to the DSM-4 TR criteria. Fluoxetine 20 mg/day and methylphenidate 40 mg/day were started as the initial treatment for the obsessions of the patient. Upon lack of response, şuoxetine dosage was increased to 40 mg/day; however, there was no reduction in the obsessions. During the follow-up period of two months, the behavioral problems of the patient in the school increased, while his sleep decreased. The patient, who displayed serious mood şuctuations, was diagnosed to have BD type-1. Fluoxetine was stopped. In the follow-up visits, risperidone was increased to 6 mg/day and valproic acid was increased to 1000 mg/day. Case 2: The sixteen-years old male was brought to our clinic with the behavioral problems at school, obsessions of cleanliness and sanitation, religious obsessions and repeated kissings on his father. He was diagnosed with OCD and ADHD according to the DSM-4 TR criteria. Sertraline 50 mg/day was started as the initial treatment for the obsessions of the patient, and the dosage of sertraline was increased to 100 mg/day in the course of follow-up visits. During this period, the patient was also given methylphenidate and risperidone treatment for ADHD and behavioral problems. The patient, who displayed serious mood şuctuations about 1 year after the beginning of treatment, was diagnosed to have BD type-2. Sertraline was stopped, and risperidone and valproic acid treatment was started. Contrary to the adult-onset BD, the PBD has rapid cycles and irritability picture is dominant. In addition, co-morbid psychiatric disorders are more frequently seen in the PBD. It is notable that these cases were interestingly resistant to the treatment that was diagnosed as BD afterwards. The fact that OCD patients who do not benefit from the treatment with SSRIs can benefit from the added antipsychotics suggest that functional abnormalities of dopamine receptors play a role in the etiopathogenesis of OCD. The overlapping signs seen in BD and ADHD patients including excessive talking, restlessness and impulsivity and frequent togetherness of these two suggest the presence of a relationship between those two disorders. PBD is diagnosed with ADHD by 60-90%. There are many studies involving ADHD and PBD. Although a high rate of co-morbidity of OCD has been shown in children and adolescents suffering BD , the numbers of studies are few. In conclusion, the PBD is frequently associated with ADHD and anxiety disorders. An increased risk for BD can be suspected in co-morbidity of treatment-resistant OCD and ADHD.