The life span of Drosophila melanogaster (Oregon R) males was found to be proportional to the logarithm of the iron content of the diet. Life span was also shown to be proportional to the rate of iron accumulation for Drosophila, mice and man. The total body iron content was found to correlate with the total calcium content of adult Drosophila. Iron content during the developmental stages, however, remained relatively constant and did not change with changes in the calcium concentrations. Dietary tea (Camellia sinensis) extracts were found to inhibit the ageing-related accumulation of iron and to prolong the life span of Drosophila by as much as 21.4%. It is concluded that iron accumulation is a significant factor contributing to senescence.