The restriction maps of the 20 kb Amy region of Drosophila melanogaster in Korean populations were surveyed from 27 isogenic second chromosome lines. A subset of these populations were also scored for isozyme type and adult enzyme activity of α-amylase. Among 34 kinds of restriction site variations that were observed in the 20 kb region surrounding the two transcriptional units of the duplicated Amy locus, nine were polymorphic (26.5%). The low frequencies at which each of the large insertions was found are consistent with earlier reports of variation in other loci. Restriction site variation in Korean populations provided an estimated heterozygosity per nucleotide pair of 0.007. Three pairwise comparisons showed relatively high levels of linkage disequilibria. The enzyme activity of the Chounan population showed no significant difference compared with that of the Pusan population, and the activity of heterozygotes was higher than that of Amy1. Lines bearing insertion/deletion exhibited relatively low enzyme activities. All lines examined showed the duplication of Amy transcriptional units that were highly conserved, and the manner of concerted evolution.