Plasma zinc levels were measured in both healthy and diabetic individuals having an age range of 10–93 years. No significant differences in plasma zinc concentrations were found between males and females in either healthy or diabetic individuals. Up to the age of 50 years, the mean plasma zinc of normal individuals remained relatively constant at 70 ± 32µg/100 ml ( ± 2 SE) after which the levels decreased. This decreasing pattern was absent in diabetics, whose plasma zinc of 65 ± 32µg/100 ml remained constant over the entire age range. For women on oral contraceptive agents, the mean plasma zinc was 59 ± 18 µg/100 ml, which was significantly lower than that of controls.