The sex-ratio trait has been described as the production of progenies with excess of females due to X-linked meiotic drive in the parental males. This trait has a variable expression in Drosophila mediopunctata. We describe here the existence and chromosomal localization of autosomal suppressors of sex-ratio in this species. There are at least four such genes (one on each major autosome) and the strongest effect.is localized on chromosome IV. These genes possibly result from the operation of 'Fisher's Principle'; a mechanism of Natural Selection leading to a 1:1 sex ratio.715546551