The functioning of the Regional Review Boards of Ontario (RRB) or their equivalents in other provinces has not been previously reviewed. This study reviews socio-demographic and clinical data of 248 patients seen between 1974 and 1983 by the RRB. The RRB heard 132 applications as 116 were withdrawn. The results are compared with 173 matched inpatient controls. Applications by psychiatrists were infrequently withdrawn or revoked. Long delays between the time of application and the hearing, and a trend towards increasing numbers of applications were noted. Schizophrenia and affective disorder were the most prevalent diagnosis with alcohol abuse and organic brain syndrome being less common among applicants. An increase in duration of stay and transfer to chronic care institutions were found among applicants. Results suggest that RRB's are not 'rubber stamping bodies' and should be more readily available and should have increased public accountability. Future changes to the Mental Health Act should be based on scientific data.