A cytogenetic analysis of the 43A-E region of chromosome 2 in Drosophila melanogaster is presented. Within this interval 27 complementation groups have been identified by extensive F2 screens and ordered by deletion mapping. The region includes the cellular polarity genes prickle and spiny-legs, the segmentation genes costa and torso, the morphogenetic locus sine oculis and is bounded on its distal side by the eye-color gene cinnabar. In addition 19 novel lethal complementation groups and two semi-lethal complementation groups with morphogenetic escaper phenotypes are described.