Genetic studies demonstrated three loci cotrolling coat colors in the Mongolian gerbil. F₁ hybrids of white gerbils with red eyes and agouti gerbils with wild coat color had the agouti coat color. The segregating ratio of agouti and white in the F₂ generation was 3 : 1. In the backcross (BC) generation (white×F₁), the ratio of the agouti and white coat colors was 1 : 1. Next, inheritance of the agouti coat color was investigated. Matings between agouti and non-agouti (black) gerbils produced only agouti gerbils. In the F₂ generation, the ratio of agouti to non-agouti (black) was 3 : 1. There was no distortion in the sex ratios within each coat color in the F₁, F₂ and BC generations This indicated that the white coat color of gerbils is governed by an autosomal recessive gene which should be named the c allele of the c (albino) locus controlling pigmentation, and the agouti coat color is controlled by an autosomal dominant gene which might be named the A allele of the A (agouti) locus controlling pigmentation patterns in the hair. The occurrence of the black gerbil demonstrated clearly the existence of the b (brown) locus, and it clearly indicated that the coat colors of gerbils can basically be explained by a, b, and c loci as in mice and rats.