Difficulty in foreskin retraction and phimosis are risk factors for penile carcinoma that may be related to the anatomically variable length of the foreskin. This observation has stimulated us to postulate the hypothesis that foreskin length is related to penile cancer. To compare the foreskin in the general population and patients with penile cancer, an anatomic classification of foreskin was designed. We examined the foreskin of 215 uncircumcised males without cancer (age range 15-93 years) and the foreskin of 23 patients with cancer (age range 31-90 years). Foreskin types were classified as long (with the preputial orifice located beyond glans meatus and entirely covering the glans), medium (with the preputial orifice located between meatus and glans corona), and short (with the preputial orifice located between corona and coronal sulcus). Phimosis was defined as a nonretractable prepuce of the long type. We found that 77% of noncancer population cases had long foreskin and that only 7% of these cases were phimotic. Cancer patients showed long foreskin in 78% of the cases, and phimosis was significantly frequent in this group (52%) as compared with the other (p <0.001). Coexistence of a long foreskin and phimosis may explain the high incidence of penile cancer in some geographic regions. To better document these findings, a comparison of foreskin types in countries with high and low incidence of penile cancer will be interesting. However, because phimosis appears to be a major factor, the presence of long foreskin may be a necessary but not a sufficient condition for cancer development. For these reasons we support preventive circumcision in patients with long and phimotic foreskins living in high-risk areas. Cancers not related to long foreskins and phimosis may be causally different.