In this study the effect of cigarette smoking on semen quality of fertile and infertile men with or without obesity was investigated. The number of fertile and infertile participants was as following: 203 fertile smokers, 78 fertile non-smokers, 147 infertile smokers and 68 infertile non-smokers. The body mass index (BMI) was measured in all fertile and infertile men. All semen parameters were assessed in both fertile and infertile men with or without obesity to identify the values that would distinguish fertile from infertile men. The results of this study showed that cigarette smoking has a significant influence only on sperm count, percentage of active sperm and sperm morphology. The semen parameters in infertile men were significantly different from that of fertile men. The influence of body mass index on semen parameters was obvious except in percentage of immotile sperms. This results suggest that the chemical agents or mutagens may affect male reproductive via direct effect on the spermatogenesis.