Abstract Background: Many schizophrenic patients are engaged in self-medication drug abuse, including narcotics. It is assumed that many of these patients have a greater number of psychotic symptoms, and show noncompliance with treatment. In this study, we investigated relationship of positive and negative symptoms and opioid dependence in these patients. Methods: This was a descriptive cross-sectional study on 100 patients with schizophrenia. The diagnoses were made based on DSM-IV criteria. After evaluating demographic data, the patients were assessed with positive and negative symptom scale (PANSS) test. Data were analyzed using SPSS10 software. Findings: Fifty percent of patients were identified to be opioid dependent based on DSM–IV criteria. Seventy five percent of patients were male and the rest were female. The mean (SD) scores of positive symptoms were 39.58 (23.374) and 54.34 (21.025) in non-dependent and dependent patients, respectively (P = 0.01). Other statistical measurements were unremarkable. Conclusion: High prevalence of opioid dependence in our sample can be due to availability of these substances in the community. Opioid may be used as self medication, can reduce the severity of positive symptoms, and may also make positive symptoms more tolerable for patients. Keyword: Schizophrenia, Positive symptoms, Negative symptoms, Opioid.