Cancer of the prostate is an important and potentially fatal disease in humans, but its etiology is yet undefined. Previous observations have shown that heavy metals play various roles in human health. The heavy metals zinc, cadmium, lead, and copper (Zn, Cd, Cu, and Pb) are known to be associated with prostate cancer, but their functions are unclear. This study examined and compared serum levels of these metals in prostate cancer patients with those of a control group. In total, 72 subjects (36 controls and 36 prostate cancer patients) were included in this study. Blood samples were collected from 36 newly-diagnosed prostate cancer patients and 36 healthy men who were matched by age, sex, race, and smoking and drinking status. After samples were prepared, serum concentrations of zinc, cadmium, lead, and copper were determined using polarography. Serum levels of cadmium and copper were significantly higher in patients with prostate cancer than in controls (p<0.05). No significant association was found between the serum levels of zinc and lead in prostate cancer patients compared with the controls (p>0.05); however, the mean concentrations of zinc and lead were higher in patients. This study supports the hypothesis that cadmium exposure increases prostate cancer risk. These findings can accelerate the diagnosis and treatment of prostate cancer. No distinct association was found between serum levels of zinc and lead and prostate cancer. More studies with larger sample sizes are needed to identify the role of heavy metals in prostate cancer.