Trace elements are essential components of biological structures, but they can be toxic at concentrations beyond those necessary for their biological functions. In the present study, groups of 35 patients with bladder cancer and 34 healthy volunteer controls were measured for trace elements using a furnace atomic absorption spectrophotometer. Serum levels of Cd, Ni and Co were increased (p<0.05) and Mn and Zn were decreased (p<0.05) in patients with bladder cancer. In the present study, a relationship was seen between the level of trace elements and the occurrence of bladder cancer, suggesting that an increase in the serum level of Cd, Ni, Co and a decrease in the levels of Zn and Mn might be important causes of bladder cancer occurrence; however, defining such a cause-and-effect relationship needs several prospective studies to be done, which seems necessary with regard to the high prevalence of this cancer.