OBJECTIVES: Cost analysis of the changes in hospitalisation for patients with schizophrenia in Spain over a 25-year period (1980-2004). METHODS: Cost analysis of the hospitalisation for patients with schizophrenia over a 25-year period based on the data exploited from the Spanish National hospital utilization databases: Minimum Basic Data Set and Survey of Hospital Morbidity. Taking into account the changes in the number of admission episodes, average length of stay (LOS) of such episodes, and costs generated per stay, an estimation of the varying hospitalisation costs in this period was carried out. RESULTS: Our data shows that the trend in hospitalisation rates for schizophrenics has increased over the entire period (3.70 in 1980 to 5.89 in 2004). LOS has substantially decreased during the study period from 148 days in 1980 to 36 days in 2004. The estimated cost per day in a psychiatric hospital for a schizophrenic patient in Spain in the year 2000 was €215.60. Some factors affecting the cost of inpatient treatment has been the evolution, consumption pattern and pharmaceutical cost of the antipsychotic drugs used in the treatment of these patients. From 1990-2001, antipsychotic consumption has almost doubled from 3.31 DID (Daily defined dose, DDD, per 1000 inhabitants and per day of treatment) to 6.04 DID. The cost of these drugs has increased 13 times, mainly due to the increase in the cost of atypical antipsychotics which has risen from representing less than 1% of the total cost in 1993 to representing 92% in 2001. The DDD cost has risen, in constant euros, from, €6.48 in 1990 to €20.31 in 2001. In addition, as a growing number of patients are being taken care of in the community, as supported by the deinstitutionalisation process, admissions into other types of institutions should be considered. There are studies showing an increase in the number of places in residential care and supervised and supported housing, having doubled in Spain from 5.1 per 100.000 population in 1990 to 10.6 in 2006. Of course, the costs per day vary greatly depending on the institution where the schizophrenic patient is placed, ranging from €67.4 per day in a day centre, to €164 per day in a long term residency or €315.7 per day in a mental health unit of a general hospital, where most stays are currently taking place in Spain. CONCLUSIONS: Following the deinstitutionalisation process of psychiatric patients that has occurred in most Western countries, in Spain, we observe an increase in admissions rates linked to a decrease in LOS for schizophrenic patients. The changing patterns of  use of hospital resources parallel to the changes in community care, mean that the costs have varied complementarily throughout this reform process. These trends could have important implications for policy makers and healthcare providers.