Previously unreported white spotting was found in two subspecies of the California vole, Microtus californicus. The pattern of spots on the ventral coat of the animals differs between the subspecies, and there is variation in the expressivity of the white spots. Expression of white spotting is greatly reduced by the epistatic action of another coat colour gene, the recessive buffy (bf). The incidence of white spotting, its variation in expression, and its inheritance were investigated in this study. The reproductive performance of white spotted voles were also analysed, and effects of fertility and litter size were found associated with the trait.