Radionuclide induced energy dispersive X-ray fluorescence was used to estimate zinc content in prostatic fluid in normal, chronic prostatitis, adenoma and cancer cases, Groups of patients suffering from chronic prostatitis, adenoma and malignant tumours consisting of 28, 28 and 13 men, respectively, were examined. The control group included 22 healthy volunteers. Expressed prostatic fluid was obtained by digital rectal massage. The zinc concentration of intact prostatic fluid was 590 +/- 45 (SE) micrograms/ml. Almost no difference was found between the zinc concentration for chronic prostatitis and for adenoma, and those for normal levels being 455 +/- 60 (SE) and 540 +/- 50 (SE) micrograms/ml, respectively. Prostatic neoplasm resulted in a significant decrease of zinc secretion, with the concentration averaging 34.7 +/- 9.6 micrograms/ml, p < 0.000001.