Cigarette smoking is a lifestyle pattern. It is a major public health problem globally and is considered as one of the most important factor responsible for decline in semen quality and overall decline in male reproductive health. The objective of this study was to evaluate the effect of cigarette smoking on semen quality in young Saudi men living in Western region of Saudi Arabia (Makkah). In this free-living population study semen samples were collected from100 men each (mild, moderate and heavy cigarette smokers) ages between 20 and 35 years with a mean age of 26.42 ± 10.69 years by masturbation with the abstinence interval of sex or ejaculate of at least 72 hours, along with 100 age matched healthy nonsmokers who served as controls. Heavy cigarette smoker group was found to be associated with significantly low levels of sperm count, concentration, sperm motility, semen volume, and percentage of morphologically (p