Authors studied serum and urine zinc levels in a total of 64 malignant melanomas. From them, in 27 patients the melanogenuria has simultaneously been observed, and the cystinuria in 35, respectively. Mentioned examinations were performed during both the recovery and relapsing periods of tumor manifestations. From the values obtained in both serum and urine, no agreement has been issued with the authors believing that the decrease in serum zinc levels and their increase in urine may be prognostically unfavorable. Similar controverting results were obtained in monitoring melanogenuria as well. In contrast, higher pathological cystinuric values resulted in 50% of tumor relapses. The authors preclude this will be the direction for further observation on by far larger group of patients.