BACKGROUND 180 psychotic patients with opiate dependence and abuse (ICD-10) were included in an open label study. The study objectives were to evaluate safety and efficacy of risperidone for a six month follow-up period. The total mean dose was 4.4 (SD: 2.4 mg/daily; range: 0.5-12 mg/daily). METHODS BPRS, CGI and DDS-SV were used to assess efficacy and UKU subscale for neurological side effects and spontaneous reports for safety. RESULTS Risperidone treatment improved symptoms, disability of the included patients with a significant reduction in the mean total scores of BPRS, CGI and DDS-SV observed from the first month of treatment onwards. Risperidone also reduced illegal opiate abuse patients from 39% basedate to 18% at month 6. There was a significant reduction (p< 0.0001) in the total UKU subscale for neurological side effects scores from visit 1 onwards for studied sample. Risperidone was well tolerated by the study patients. From 165 elegible patients, just 10 (6.1%) discontinued treatment due to adverse reactions, 94% of the patients did not suffer any adverse event; the most frequent adverse events according spontaneous reports were extrapyramidal effects (3%) and anxiety (1.8%). CONCLUSIONS Risperidone improved disability, psychotic symptoms and tolerability of these patients. Those results could mean an outstanding breakthrough in the treatment of these type of disorders and, if it is confirmed that risperidone can lead to abstinence, we would be before a new line of treatment for dual pathology.