The element Zn is the metal component or activator of many important enzymes. The tissue concentrations and activities of Zn metalloenzymes direct the rate of protein and nucleic acid syntheses, thereby influencing tissue growth and reperative processes. Most of the serum Zn is normally bound to circulating proteins. Low serum Zn concentrations might result from depletion of Zn-binding proteins. Serum protein and Zn concentrations have been reported to be depressed in patients with acute and chronic diseases. We compare the serum protein and Zn values of patients with thoracic empyema (n = 20) with those of a control group (n = 20). The values obtained in the empyema group were significantly lower than those in the control group before the study. Test group administered 220 mg zinc sulfate (ZnSO4.7H2O) over 20 d and there was a significant increase in the values for serum protein and Zn after the oral administration of the zinc sulfate.