BACKGROUND: It has been reported that approximately 1% of young women have anorexia nervosa and 4% bulimia. Managing eating disorders requires a multi-disciplinary approach including acute hospitalization, when necessary. This study was undertaken to assess the cost of acute hospital care for these disorders. METHODS: Inpatient cost estimates, adjusted for medical inflation and cost-to-charge ratios, were developed using data from all-payer 1998 discharge databases from five states, supplemented with national fee schedules. ICD9 codes were used to identify those with a principal diagnosis of anorexia (307.1) or bulimia (307.51). Cases where both diagnoses were coded are excluded from results reported here. Log transformation was used to address highly skewed distributions. Length-of-stay (LOS), disposition and psychiatric unit care (PSYU) were also examined. Hospital costs (i.e., accommodation, ancillary, physician) are reported in 2000 US$. RESULTS: The state databases yielded 641 cases of anorexia and 326 of bulimia. The overwhelming majority (>96%) were females. For anorexia: the mean age was 25 years (45% <20 years); mean LOS was 13; 24% received care in a PSYU; 87% were discharged home; 7% went to a rehab or mental health facility (MHF) and 3% left against medical advice (AMA). For bulimia, the mean age was 27 years (25% <20 years); mean LOS was 9; 39% received care in a PSYU; 90% were discharged home; 4% to rehab or MHF; 3% left AMA. The mean total cost per hospital stay was $12,390 for anorexia and $9,120 for bulimia. On average, the number of annual admissions was 1.6 and 1.2 for anorexia and bulimia, respectively. Managed care was the largest primary payer. CONCLUSIONS: Although hospitalization is not the primary site of medical care for managing serious eating disorders, it’s sometimes required. We believe that this information provides an essential piece in understanding the economic consequences of these conditions.