Numerous studies have identified specific body systems affected by the hazardous effects of the cigarette smoking particularly the respiratory and cardiovascular systems. The effect of smoking on male reproduction has also been studied where semen quality was investigated in different cross-sectional studies including infertile patients with conflicting results. This article aimed to assess the relationship between smoking and male infertility. A review of published articles was carried out, using PubMed, medical subject heading (MSH) databases and Scopus engine excluding the effects of smoking outside male infertility. Key words used to assess exposure, outcome, and estimates for the concerned associations were: smoking, semen, male infertility, sperm, humans, and fertility. Most of the reports showed that smoking reduces sperm production, sperm motility, sperm normal forms and sperm fertilising capacity through increased seminal oxidative stress and DNA damage. Few papers reported nonsignificant differences in semen parameters between smokers or non-smokers. It is concluded that although some smokers may not experience reduced fertility, men with marginal semen quality can benefit from quitting smoking.
