Abstract
The study was made to establish methods for estimating the recombination values in 3-point backcross data in the housefly, Musca domestica when the penetrance of a character was incomplete, and the viability of each gene employed or analyzed was not equal to that of the wild allele. The principle of the methods may be applicable not only to insecticide-resistance characters, but also to various morphological, physiological or biochemical characters, such as radiation tolerance enzyme activity, lethal or semi-lethal effects, etc.