Fifty-three psychiatric hospital inpatients with a dual diagnosis of substance abuse and schizophrenia were given the Brief Symptom Inventory and the Schizophrenia/Substance Abuse Interview Schedule. Mean age was 29; 49 were men. Only 11% were employed. Forty percent abused mainly alcohol, 40% cannabis and 8% amphetamines; 20% abused more than one substance. Mean onset age of drug abuse was 16 years; schizophrenia was diagnosed a mean of 5 years later, and subjects had been admitted to hospital an average of 7 times since then. Most believed that drug abuse initiated or exacerbated their schizophrenia; 80% took drugs primarily to relieve dysphoria and anxiety. Amphetamines improved subjective well-being significantly more than alcohol, but choice of drugs was determined mainly by price and availability. Only cannabis increased positive symptoms of schizophrenia and only amphetamines reduced negative ones. Effectively treating this population requires an integration of psychiatric and drug treatment services, ideally in a community context.