ABSTRACTIn a group of 71 inpatient schizophrenics with no other concurrent psychiatric diagnosis except for dependence on one drug, we ascertained the subjective effect their drug of abuse had on their psychiatric symptoms 2 weeks prior to hospitalization. Psychiatric symptoms were assessed by means of the Hopkins Symptom Checklist (Revised) (SCL-90R). Cocaine addicts, but not alcoholics, reported aggravation more often than improvement of symptoms. Alcoholics reported alcohol-induced symptom improvement with a similar frequency as alcohol-induced symptom aggravation.