A reference range data base containing serum chemistry and hematology values on over 3000 animals is described. Data listed include the mean, standard deviation, and 10th and 90th percentiles for each of the following parameters. Serum chemistry: sodium, potassium, chloride, calcium, inorganic phosphorus, urea nitrogen, creatinine, total bilirubin, total protein, glucose, cholesterol, triglycerides, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma‐glutamyl‐transferase (monkey only), lactate dehydrogenase (dog only), and creatine kinase (dog only). Hematology: hematocrit, hemoglobin, red blood cells, reticulocytes, mean cell volume, mean cell hemoglobin, mean cell hemoglobin percent, platelets, white blood cells, neutrophils, eosinophils, basophils, lymphocytes, monocytes, and stabs. The species included are mouse, rat, hamster, rabbit, beagle dog, and cynomolgus monkey. The use of the reference ranges in routine computerized data collection is discussed.