Copulation duration differed between black and brown morphs of Drosophila elegans: longer in the former than in the latter. Experiments on copulation between these two morphs revealed that copulation duration was determined by both sexes. The genetic analyses using F₁ hybrids and recombinant inbred lines suggest that two or more loci were responsible for the differences in both of male and female properties for the determination of copulation duration between the black and brown morphs and at least one of the loci governing the male property was probably located on the X chromosome. It also appeared that loci responsible for the difference in copulation duration of males between the brown morph and black morph strains differed from those responsible for the difference in copulation duration of females between them. Genes controlling male copulation duration are at least partly linked with a gene controlling body coloration.