Zinc and cadmium in both serum and erythrocytes from patients with prostatic carcinoma of different histologies, BPH, other urological tumors, and pyelonephritis were analyzed by atomic absorption spectrometry. The variance of the results obtained was very high for each group. No significant differences in the Zn or Cd concentration in either the blood plasma or the erythrocytes could be found between any of the different groups of patients. There were also no trends to be seen in the concentrations of these elements in human blood over a period of months. We conclude that the concentration of Zn and Cd in serum or erythrocytes are not an index for the diagnosis or therapy of prostatic carcinoma, BPH, urological malignancy, or inflammations.