Objective: Many studies have linked smoking to male infertility. Therefore, we aimed to investigate the effect of smoking on sperm parameters in men with suspected infertility in the Turkish population. We also examined the effect of daily smoking amount and smoking duration on sperm para-meters.

Material and Method: This study consisted of 1005 men (smokers= 599, non-smokers= 406) with suspected infertility. It evaluated sperm parame-ters, including, leucocyte count, sperm concentration, total sperm count, motility, and the total progressive motile sperm count in these men.

Results: In our study group, 59.60% were smokers and 40.40% were non-smokers. Body mass index (BMI) was higher in non-smoker males. Sperm characteristics were similar in smokers and non-smokers. We evaluated the smoker\'s group according to the number of cigarettes smoked per day. There was no significant difference in sperm parameters between the group that smoked up to 30 cigarettes a day and the group that smoked more than 30 cigarettes. Then, we examined the smokers in 3 groups according to the duration of smoking: 0-10 years, 11-20 years, and 20 years and over. It was observed that non-progressive motility was the lowest and immotility was the highest in smokers who had been smoking for 20 years or more.

Conclusion: This study is the most comprehensive study in Turkey examining the relationship between smoking and sperm parameters to the best of our knowledge. Our results show that the duration of smoking affects sperm functions. Our evidence indicates that men with suspected infertility should quit smoking to optimize their successful conception.