The Polycomb group (Pc-G) of genes are thought to work together to repress the expression of the homeotic genes. We prepared a double mutant of Scm and pho and examined their effects on the formation of the adult structures. While pho homozygotes are viable, ScmDI/+:phoCV/ phoCV double mutant individuals die as pharate adults, showing strong homeotic transformation in legs and tergites. The second and third legs were transformed to the first leg and the claw to the sixth tarsal segment. A few extra sexcombs were found on the second tarsal segment. These results indicate that the interaction of Scm and pho cause the transformation of the distal structures to the more proximal structures in thorax appendages as well as the homeotic transformations. As the phenotype of the double mutant is stronger than the addition of each phenotype, they appear to interact synergistically to repress the expression of the homeotic genes.