Restriction maps of a 12,000-nucleotide region containing the alcohol dehydrogenase (Adh) locus of the second chromosome of Drosophila were determined for (i) 18 independent second chromosome stocks of D. melanogaster established from several natural populations and (ii) five closely related Drosophila species. All of the detected map differences appear to lie outside the Adh coding block. Four polymorphic restriction sites and four insertion/deletion variants were identified among D. melanogaster chromosomes. The estimated heterozygosity per nucleotide site was 0.006. The relative distributions of restriction sites and insertion/deletion variations among subpopulations and species suggest that the insertion/deletion variation may be mildly deleterious.