OBJECTIVES To estimate hospitalization costs as well as resources used by schizophrenic patients during a relapse in a public psychiatric hospital. METHODS A documental retrospective analysis of schizophrenia patients with a relapse as the principal diagnosis was carried out in a public psychiatric hospital in Mexico. The range of patients' age was from 18 to 64 years. Data was collected by a General Physician through a Case Report Form designed specifically for this study. Resources used during relapse hospitalization were accrued and final costs were calculated using unitary costs of the Mexican Social Security Institute (IMSS) for laboratory studies, physician's visit, emergency admittance and bed day. Drug costs were obtained from public bids of the same institution. Results are presented using descriptive statistics. Costs are in US dollars using and exchange rate of 13.5 MXN pesos for 1 US dollar. RESULTS Sample size was of 73 patients with an average follow up of 3.3 years. Hospital average length of stay was 20.65 days (4 – 108), average time between relapses was 14.66 months (6.47 – 25.73). The average cost per day was $ 346 (95% IC, $ 331 – $ 360), 96% of this cost represents the average bed day cost reported by the IMSS. The average cost per relapse was $7,086 ($1,498 – $36,288). Alcoholism and hypertension were the main comorbidities reported in 10.8% of admitted patients. Lack of compliance was the reason for relapse in 95% of the cases. CONCLUSIONS Bed day cost is the main component of total costs, therefore it would make sense to use those antipsychotic drugs that help reduce the hospital length of stay. The lack of compliance is responsible for the vast majority of relapses (95%). A health care program focus in increasing drug compliance could decrease institutional general costs by reducing hospitalizations due to relapses.