Smokeless tobacco is used in various forms in some countries of the world. "Maras otu" is a kind of smokeless tobacco usage in the Southeastern region of Turkey. The use of smokeless tobacco causes nicotine addiction and dependence. Moreover this type of smokeless tobacco usage is one of the risk factors for oral cancers and genotoxic damages for users. Cotinine is widely used as a biomarker of tobacco consumption and intake of nicotine. Therefore, urine samples were collected from people who are using Maras powder and smoking cigarettes, and passive smokers, and the levels of cotinine investigated. The purpose of this study is to determine the cotinine levels of Maras powder users and to compare the results with cigarette smokers and passive smokers. Urinary cotinine levels of subjects were determined by using capillary gas chromatography with FID detection. The mean (+/-SD) urinary cotinines have been determined as 6467.35 +/- 3198 mug/g creatinine for 26 Maras powder users, 1943.92 +/- 1443 mug/g creatinine for 26 cigarette smokers and 198.62 +/- 420.82 mug/g creatinine for 26 passive smokers. A significant difference has been found between cotinine levels of Maras powder users and cigarette smokers, which is three times higher in Maras powder users (p < 0.001). The present study suggests that smokeless tobacco poses a threat to public health and it should not be viewed as a safe alternative to cigarettes.