Objective: This study was undertaken to investigate possible differences in clinical, social and hospital prognosis in schizophrenics with or without codiagnosed alcoholism. Method: A representative sample was selected by a two-stage random sample of sets from the total of 10,569 schizophrenic patients registered in the Croatian Psychotic Case Register in the period 1962-71. The resulting 449 schizophrenic patients were psychiatrically examined in 1973-75 wherever they were found-at home, in a hospital or in a social-health institution. Of these original patients, 312 with or without a dual diagnosis of schizophrenia and alcoholism who were found at home were followed up until the final examination in 1990-91. Results: Rate changes in 37 patients with the dual diagnosis were significant in the following characteristics: they were more often men, married, with a paranoid-hallucinatory disease form, were aggressive during examination, and were without psychiatric aftercare or regular psychopharmacotherapy (p < .01); they came from rural areas, had a mixed clinical picture with a deteriorating disease course and were less communicative and socially functional, and were without work self-initiative and personal income (p < .05). Conclusions: Schizophrenic patients found at home with codiagnosed alcoholism have poorer clinical, hospital, social and life prognosis and need longer hospitalization. They represent a special subgroup of schizophrenics requiring special therapeutic approach and early identification, inasmuch as their course of the disease has a tendency toward rapid deterioration. Prevention of alcoholism and its adequate treatment have far reaching implications for the prognosis of schizophrenic illness.