Hospital records of 72 drug abusers with psychoses (DAP) were analyzed to clarify the relationship between drug abuse and psychosis. Comparison groups included schizophrenics and atypical schizophrenics without drug abuse and drug abusers without psychoses (DA). Compared with DAP in whom psychoses lasted less than six months before admission (DAP-short), drug abusers with psychoses of a longer duration (DAP-long) had more symptoms, more premorbid personality disorders, and greater familial risks of schizophrenia and affective disorder. The DAP-long group resembled atypical schizophrenia for clinical features and family history, whereas the DAP-short group resembled DA for some clinical features and family history. The results indicate that there are several subgroups of DAP. The importance of clinical features and family history in identifying subgroups of DAP was stressed.