Objective. The randomized comparative study of aripiprazole and quetiapine in the treatment of patients with “dual diagnosis” of schizophrenia and drug addiction. Material and methods. Intra-group analysis of dependent variables on the scales PANSS, BPRS, VAS, SACS showed significant differences in the dinamics of the therapy in all groups. A comparative randomized study included 90 men admitted to an inpatient addiction unit. Of these, 54 (60%) had a previously established psychiatric diagnosis and 36 patients (40%) did not have an established psychiatric diagnosis. They were randomized into 3 groups of 30 patients each: group 1 received aripiprazole at a dose of up to 20 mg/day, group 2 received quetiapine at a dose of up to 600 mg/day and group 3 (controls) was treated with haloperidol at a dose of up to 30 mg/day. Treatment duration was 21 days. The efficacy of aripiprazole and quetiapine was evaluated with PANSS, BPRS, VAS and SACS on 10th, 14th and 21st day (visits 2—4). Drug safety was evaluated by recording adverse events or side-effects. Results and conclusion. An analysis of independent variables showed significant differences between aripiprazole and haloperidol in PANSS and BPRS scores at visit 4, in VAS scores at visit 3, and in SACS scores at visit 2. An intergroup analysis of independent variables showed significant differences between quetiapine and haloperidol in PANSS, VAS and SACS scores at visit 4 and between aripiprazole and quetiapine in VAS and SACS scores. According to the results of the correlation analisys it has been concluded that presenting features of schizophrenia are closely correlated with drug addiction (craving).