Cervical intraepithelial lesions were diagnosed cytologically, and confirmed histologically in 328 patients from 1990 to 1996 at the University Hospital of Heraklion. The women were grouped according to the grade of the cervical intraepithelial lesion as low grade cases (LSIL) on high grade cases (HSIL) (Bethesda classification). They were also grouped according to their smoking status as non-smokers or smokers. A very strong statistically significant difference (p < 0.0001) in the incidence of the disease between non-smokers and smokers was found, to the disadvantage of smokers. Also a very statistically significant (p approximately 0.001) association was found between the number of cigarettes per day, duration of exposure (years of use) and the grade of cervical intraepithelial lesion. Our results indicate that cigarette smoking is a risk factor in the development of cervical intraepithelial lesions and possibly cervical squamous cancer. Further studies are required to prove this hypothesis and to document the biological plausibility of this relationship.