ABSTRACT INTRODUCTION FAMILIAL differences in the incidence of mortality due to blue comb disease in chickens were reported by Cole (1950) and by Moultrie, Cottier and King (1955). The exact relationship between blue comb disease and uric nephritis in chickens is somewhat uncertain. Jungherr (1952), after reviewing the evidence of the close clinical resemblance of blue comb disease to both spontaneous and experimentally induced cases of uric nephritis, suggested that blue comb disease may be the acute form of uric nephritis. There were no differences in the levels of nephritic mortality among the inbred lines of the Poultry Research Centre at Edinburgh, Scotland, as reported by Spector (1951). On the other hand, Hicks (1953) has reported differences between families within strains and differences between breeds with regard to the occurrence of nephritis. Similarly, Biely and March (1957) found differences in the incidence of nephritis among several unrelated strains of S.C. White . . .