The data presented are compiled from two herds of American bison (Bison bison) in Kansas. In this study there were differences in the mean values of white blood cell count, neutrophil percentage, lymphocyte percentage and cholestrol, alkaline phosphatase, specific glutamic-oxalacetic transaminase concentrations between the age groups of animals under 2 years of age and bison over 2 years old. Differences in the two age groups paralleled those found in Jersey and Hereford cattle. Packed cell volume and hemoglobin concentration was considerably higher than found in domestic Bovidae. More data is needed from other bison herds in this country to better describe the range of normal variation in individuals, population and age groups of B. bison.