OBJECTIVE: To determine the economic impact of Bipolar Disorder (BD) from an employer perspective. METHODS: Medical, pharmacy, workers' compensation (WC), short- and long-term disability (STD, LTD), and sick leave (SL) costs were examined in a database consisting of 2001-2002 claims, payroll, and demographic data from more than 6 large US based employers. Regression modeling was used to measure the cost differences between employees with BD and employees without BD while controlling for age, tenure, gender, salary, region, and other factors. RESULTS: Data were available for 761 employees with BD and a control group of 229,145 employees without BD. The BD group had higher costs with a 217% difference ($6836) summed across all measures (P °Ü0.05). The individual differences in medical and pharmacy costs were $3860 and $1866, respectively. Work absence costs had differences of $80 (SL), $254 (WC), $668 (STD) and $108 (LTD). CONCLUSIONS: The impact of BD can be costly, not only in terms of healthcare costs, but also in its impact on lost productivity due to absenteeism. Employer-based interventions focusing on managing BD should be evaluated and implemented to manage potential short-term and long-term economic impact.