The gene products of the two major alleles of alcohol dehydrogenase (ADH-F and ADH-S) have been subjected to kinetic and biochemical analyses over a range of temperatures. Although temperature was found to have a significant effect on both kinetic and biochemical properties of Drosophila ADH, no significant differential effect was observed between the major ADH allozymes. The results are discussed within the context of the selective maintenance of Adh polymorphism in natural populations.