Normal hematological and blood chemistry parameters were measured in 45 American bison (Bison bison) that were divided into three age groups for comparison. There was a statistically significant (P < 0.05) increase with advancing age in mean corpuscular volume, mean corpuscular hemoglobin, absolute neutrophil and eosinophil counts, total protein, globulin, creatinine, and blood urea nitrogen. There was a statistically significant (P < 0.05) decrease with advancing age in levels of sorbital dehydrogenase, alkaline phosphatase, glucose, sodium, calcium and phosphorus.