Serum selenium levels were determined in 92 healthy subjects [40 men, 52 women; mean age 33.5 +/- 1.6 (s.e.m.) years, range 16-71 years] living in the province of Barcelona, Catalunya, Spain. Only well-nourished individuals with unremarkable clinical history, normal blood chemistry and haematological tests were selected. The subjects were divided into 6 age groups for each sex. Serum samples were analysed using a modification of the standard electrothermal graphite furnace atomic absorption spectrophotometry method to shorten the procedure while maintaining its accuracy. A significant correlation (y = -1.31 + 1.51 x; r = 0.9967, P less than 0.001) was observed between our method and the standard assay method. The mean serum selenium concentration was 60.39 micrograms/l, 95 per cent CI 53.35-67.45 micrograms/l. There were age- but no sex-group differences (P less than 0.001). This result is similar to that found in countries whose low selenium levels have been related to an increased risk of some disease states. Clinical and health implications of this suboptimal selenium status are discussed.