OBJECTIVE: The aim of the study was to synthesize previous research findings on the outcomes of patients who had received psychiatric hospital treatment. METHODS: The authors reviewed 54 follow-up studies of psychiatric hospitalization of adults published between 1975 and 1992 and identified ten predictor variables that were examined in at least five of the studies. The findings for each predictor variable were integrated using a system that weighted findings based on the sample size and the time from discharge to follow-up assessment. RESULTS: The five most powerful predictors of outcome were type of onset of illness, previous hospitalization, age at onset of illness, use of medication, and marital status. Predictor variables with moderate associations with outcome included diagnosis, gender, precipitating factors, and duration of illness. Length of stay showed no significant relationship to outcome. CONCLUSIONS: Future studies of the outcome of psychiatric hospitalization should carefully define successful outcome, delineate the dimensions of hospital treatment, and explore a wide range of predictor variables.