Ageing is a complex phenomenon with possibly a multitude of contributions from many genes. In our study, we tested the degree of contribution of alcohol dehydrogenase (Adh) polymorphism (as specific enzyme activities) to ageing in Drosophila melanogaster. Our results indicate an overdominance of FS genotypes on ageing flies, with the two homozygotes, i.e., FF and SS, having significantly lower mean longevities. However, that kind of life-span-genotype relationship was not detected when the genotypes were observed for the immediate function of the Adh locus, ADH enzyme activity in which mean ADH-FF activity was the highest as compared to those of ADH-FS and ADH-SS. This irrelevancy of the ADH enzyme function to ageing, with an obvious overdominance effect of Adh locus, is discussed considering Adh's known relation to other life history traits.