The present work was conducted to investigate the possible use of epithelial cells from the oral cavity and urinary tract in identifying smoking-related effects in men. Epithelial cells from the oral cavity and urinary tract were collected from 25 smoking and 25 non-smoking men and subjected to micronucleus assay. The DNA damage (cells with micronuclei and nuclear buds), binucleated cells, condensed chromatin, karyorrhexis, pyknotic and karyolytic cells were observed after DNA specific staining. The analysis revealed the frequency of binucleated cells and condensed chromatin cells in 25 studied men with smoking habit, statistically significant differences were noted only in epithelial cells from the oral cavity in comparison to those of the urinary tract. In non-smokers the results demonstrated no differences in cytogenetic damage frequency in cells collected from the oral cavity and isolated from the urine. The differences in the observed frequencies of micronuclei in buccal and urothelial cells could be an effect of the smoking in the sampled group, smoking pattern of the men and the number of cigarettes smoked per day.