This review considers the use of day hospitals as an alternative to out-patient care. Three types of day hospital are covered by the review: 'day treatment programmes', 'day care centres' and 'transitional' day hospitals. Day treatment programmes offer more intense treatment for patients who have failed to respond to out-patient care (usually patients with affective or personality disorders). Day care centres offer structured support to patients with long-term severe mental disorders (mainly schizophrenia), who would otherwise be treated in the out-patient clinic. Transitional day hospitals offer time-limited care to patients who have just been discharged from in-patient care.