Second instar larvae of Drosophila melanogaster were exposed to exogenous alcohol, which is known to influence the activities of several enzymes. In this study, the activity changes were followed in four enzymes (ADH, ODH, alpha GPDH and AOX) during ethanol exposure and compared in three inbred lines that had different allelic combinations at the Odh and Aldox loci. The results indicate that the Odh-Aldox region of the third chromosome may alter the general response to ethanol. The activity of ADH increased considerably in two strains in the larval stages in the presence of alcohol; nevertheless, strain 1, with the OdhS-AldoxF allelic combination, showed a delay in the ADH induction compared to strain 2, which had the OdhF-AldoxS combination. In strain 3 (OdhS*-AldoxS) larvae, ADH induction by environmental ethanol was not detected. Moreover, the activities of alpha GPDH and AOX in strains 2 and 3 were not affected by ethanol. In contrast, the activities of all four enzymes in strain 1 changed after exposure to ethanol.