Apparently healthy free-living (non-hospitalized) men aged 8-89 years (n=408) were studied to determine the effect of age on serum copper and zinc concentrations and the copper/zinc ratio. Mean values ± S.D. for age, serum copper and zinc levels and the copper/zinc ratio were as follow: 41.9 ±22.9 years, 1.15 ± 0.17 ¿rg/ml, 0.93±0.14 /¿g/ml and 1.25±0.19, respectively. In the elderly subjects above 75 years, a marked increase in serum copper concentrations and the copper/zinc ratio as well as a decrease in serum zinc concentrations were observed. Serum copper concentrations and the copper/zinc ratio correlated positively with age (pcO.OOOl).