The objective of the present study was to examine the efficacy of group musical therapy for inpatients with DSM-IV schizophrenia or schizoaffective psychosis. Thirty-four therapy group subjects in a ward for long-stay female patients received 15 group musical therapy sessions over 4 months, while 32 waiting group subjects from another ward with the same function were to wait for the sessions until the studied course was completed. The assessment included measures of psychotic symptoms, objective quality of life and subjective musical experiences. Comparison of the groups indicated that significant advantages in the therapy group subjects were detected in some measures concerning personal relations and a subjective sense of participation in a chorus activity. However, the follow-up evaluation suggested that the improvement might not be durable. These findings suggested that the musical therapy had some, but possibly only short-lived, effects on personal relations and musical experiences of chronic psychotic patients.