OBJECTIVES:  To study the treatment pattern and cost of illness in bipolar disorder patients in tertiary care hospital in South India METHODS:  A retrospective study was conducted in a tertiary care teaching hospital of South India. Data were collected retrospectively from medical record section from 2012 to 2013 in suitable designed case record form. Data were analysed by using SPSS 20.0. RESULTS: Total of 100 cases of bipolar disorder was followed during the study period. Among them 66 were males and 34 were females. The mean age of the study population was found to be 46.2+13.3 years.  Among the social history 13 people were alcoholic and 60% of the study population had a family history of known psychiatric disorder. The mean duration of illness of the study population was found to be21.8+9.8years.  Among the study population 34 patients were diagnosed with mania and 46 patients diagnosed with depression. Mood examination revealed that 38 patients were happy followed by 22 patients were irritable. Affective examinations showed maximum were euphoric. Insight examination showed Grade 1 predominance. The different treatment pattern revealed that all of them were prescribed with mood stabilizer followed by anti-psychotic (93) and hypnotics (86). The average hospitalization cost of the patient was found to be 7477.83 + 5989.67 Rupees with median hospital stay of 7(5) days. The average treatment cost constitutes total 50% of the hospitalization cost. CONCLUSIONS: Mood stabilizers and anti-psychotics were the main treatment strategies among the bipolar patients and drug cost consumes 50% of the total cost of hospitalization. Pharmacoeconomic studies plays important role in estimating the total healthcare burden in bipolar disorders.