Abstract Backgrond: Drug abuse, especially opium abuse, is a major public health problem in Iran. Recent reports suggest that opium sellers cheat their customers by adding lead to the opium. Contaminated opium can threaten the health of consumers. The present study aimed to compare the serum level of lead between opium dependents and a control group. Methods: This was a cross-sectional study in which 50 opium dependents aged 20 to 60 years old were compared with a control group of 43 non-dependents who were matched with the case group in terms of sex and age. The serum level of lead and liver function tests including serum total bilirubin, AST, ALT, Alkaline-phosphatase and hemoglobin were measured for all subjects. Findings: The mean level of serum lead concentration in opium dependents and controls was 3929.358 ± 147.67 and 3532.721 ± 1141.53, respectively and the difference was not statistically significant. There was no significant correlation between serum level of lead and age, duration of opium dependency, serum total bilirubin, hemoglobin, AST, ALT, and Alkaline-phosphate. Conclusion: Although there was no significant relationship between opium consumption and serum level of lead, the concentration of lead in dependents' serum was higher than controls. Further studies are needed to approve this relationship to be used for screening and on time diagnosis of opium dependents. Keywords: Opium, Addiction, Lead poisoning, Serum level.