Background: A series of biochemical reactions are involved in the endogenous production of estrogens. Their final and rate-limiting step is catalyzed by aromatase belonging to the class XIX of cytochrome P450. CYP19 is a key enzyme for estrogen synthesis in males. It catalyzes the irreversible conversion of androstenedione and testosterone to estrone and estradiol-17&beta, respectively. Aromatase P450 is present in the endoplasmic reticulum of estrogen-reproducing cells in which it is expressed. The effects of the resulting estrogens are mediated through the estrogen receptor. One of the most important polymorphism, is a C to T variation in exon 7 resulting in an Arg264Cys amino acid exchange, has been shown to be very common in Asia. The purpose of this study was to determine the association of CYP19 gene polymorphism with the prostate cancer risk among the studied population. Methods: PCR-RFLP analysis of CYP19 gene was on 100 prostate cancer patients and an equal number of matching controls. The data was analyzed using the computer software SPSS for windows (version 19). Results: The frequency of CT genotype was higher in patients (37%) as compared to controls (21.2%) and this incidence was statistically significant (OR, 2.10 95 % CI, 1.02-4.34 P=0.044). Stratification of patients according to the risk factors, resulted in a slightly improved OR in individuals carrying CT compared to CC genotype (OR, 2.35 95% CI, 1.11-4.96 P=0.024). The TT genotype was not significantly associated with prostate cancer risk (OR, 0.63 95% CI, 0.16-2.50 P=0.519). Conclusion: It seems that CT genotype is more associated with cancer prostate compare with other genotypes. It appears to be an increased risk of prostate cancer associated with the Arg264Cys substitution in the CYP19 gene.