The purpose of this study was to investigate the factors predicting readmission and the interval between readmissions to psychiatric hospital during the early 1990s in Finland. Data were retrieved using the national register of all discharges from psychiatric hospitals during the early 1990s. Frequently admitted patients were an identifiable group. The factors associated with an increased risk of multiple readmissions were: previous admissions, long length of stay (LOS) and diagnosis of psychosis or personality disorder. Patients with psychosis or personality disorder were also readmitted more rapidly than patients with an organic disorder. There seemed to be a small proportion of psychiatric patients in need of frequent or lengthy hospital treatment. The expansion of community care did not as such seem to have diminished the need and use of psychiatric hospital care. However, the differences between the years 1990 and 1993 were less important than the other factors that predicted readmission, namely LOS and diagnosis.