The life span of Drosophila melanogaster was reduced when copper compounds were fed at concentrations of 1 X 10(-3) M or greater. Feeding lower concentrations of copper compounds failed to significantly change life span. A combination of copper gluconate and gluconic acid increased the adult life span by 21.6%. We conclude that only an extraordinarily high dietary intake of copper would accelerate senescence. Dietary gluconic acid retarded the normal age-related accumulation of copper in adult flies.