Common laboratory rodents have always been a favorite choice as a pet. Although diagnostic clinical pathology has not been viewed as practical for the rodent patient, current advances in technology make processing of small samples possible. Cultivation of the technical skills necessary for rodent sample collection has the potential to improve the standard of rodent veterinary care. This article provides an overview of rodent sample collection techniques, hematology, clinical biochemistry, serology, and clinical pathology of other tissues and fluids for laboratory rodents. General principles of clinical pathology can be applied across species. This article emphasizes the subtleties of the different rodent species which may impact diagnostic interpretation.