Introduction: Calcium has anti-proliferative and pro-differentiation effects on cells in vitro and can inhibitthe development of various cancers. While there is some epidemiologic evidence for an inverse relation betweendietary calcium intake and prostate cancer risk, only few have focused on serum calcium levels in this respect.Materials and Methods: We assayed total serum calcium and ionized serum calcium in a pilot study of 40prostate cancer patients and compared with 40 healthy controls. Results: Our observations provided evidencefor an association between prostate cancer risk and total and ionized serum calcium levels(p=0.020 and p≤0.001respectively). The mean difference of total serum calcium was also significant in patients with serum PSA >20ng/ml (p=0.017). Conclusion: This is an important and interesting finding which requires further exploration intomechanism involved in calcium channel and prostate cancer risk in a larger cohort of different ethnic population.