Recent studies suggest that chronic inflammation is crucial in the development and progression of prostate cancer (CaP). Interleukin-6 (IL-6) is a proinflammatory cytokine that plays an important role in intraprostatic inflammation and thus carcinogenesis. The -174G > C polymorphism of IL-6 gene has been associated with high IL-6 producer phenotype and an increased risk for CaP. The aim of this study was to evaluate the association between the mentioned IL-6 polymorphism and CaP risk, as well as to compare the genotype frequency between the different tumour grades of CaP, in population of Eastern Croatia. We analyzed the IL-6 polymorphism in 120 CaP patients and 120 controls with benign prostatic hyperplasia (BPH). CaP patients and BPH controls did not statistically differ in studied IL-6 polymorphism. Furthermore, high IL-6 producer genotypes (GG or GC) were more frequent in controls than in CaP group (86.7% vs 80.8%, respectively, p = 0.147). Also, no statistically significant difference in IL-6 high and low producer genotype frequency was noticed between well, moderately and poorly differentiated tumours. Our results, taken together with other studies on the subject, suggest that IL-6 - 174 single nucleotide polymorphism (SNP) distribution may differ between various ethnic groups and that a single cytokine gene polymorphism has probably just a minor effect on CaP susceptibility. Further studies should be performed to clarify the link between SNPs of different cytokines and the risk for CaP.