Prostate cancer is one of the most common types of cancer in men. A total of 110 Iraqi Arab individuals were included in this study; 60 individuals of them had prostate cancer with increased levels of TPSA (patients group); their age range 52-90 years. They were referred for diagnosis and treatment to the National Al-Amal Hospital for oncology in Baghdad during the period from July 2017 to October 2017. While the other 50 apparently healthy subjects were the control group, their age range similar to patients group. Sera and blood samples were collected from all patients and controls than used to assess for the level of IL-18 and DNA extraction, respectively. The polymorphisms were analyzed using polymerase chain reaction-single specific primer (PCR-SSP), at the position -137 G\C (rs187238) in the promoter of IL18 gene. The genetic polymorphism of the IL18 gene promoter -137G/C (rs187238) was determined and presented with three genotypes (GG, GC, and CC) in prostate cancer patients and controls. Testing for Hardy-Weinberg (H-W) equilibrium revealed that Prostate cancer patients showed insignificant variation in the distribution of IL-18 -137 genotypes (P> 0.05). While the control samples showed significant variation (p ≤0.05) between the observed and expected. Comparing patients with controls indicated that IL-18-137 alleles or genotypes showed no association with the risk of prostate cancer development in Iraqi Arab population or protection against them. Serum level of IL-18 was highly significant (P ≤ 0.001) increased in patients compared to control. The IL-18 serum levels differences in GG and GC genotypes was significant (p <0.05) between patients and control. While there were no significant differences between the three IL-18 -137 genotypes inpatient or in controls.