Comparing to other health problems, substance use epidemiology is a new area of research in Iran. The aim of this study was to determine the prevalence of opioid use among referees to a clinical laboratory by drug testing.Methods: In this cross-sectional study, the urine sample of 1120 consecutive individuals referred to a major clinical laboratory in Kerman city were tested for opioid metabolites anonymously. At first, a screening test was done on samples (chromatographic Immunoassay test, ENISON, U.K) and then solid-liquid column chromatography and thin layer chromatography (Sam phannavar, Tehran, Iran) was done on positive samples as a confirmatory test. The results were analyzed using Chi-Square test and descriptive methods.Results: Ninety-three percent of subjects were urban dwellers and the mean (±SD) age of the sample studied was 46.5 (±16.5). In 28.4% (318) of the specimens the screening test became positive and thin layer chromatography confirmed half of them as true positive. So, 14.4% of samples were positive regarding opioid metabolites.Conclusion: Although individuals attending laboratory clinics may not be a representative sample of the whole Kermani population, but the relatively high figures obtained have significant implications for further research.