The extraction of multiple body fluids samples is frequently necessary when research studies involving laboratory rodents are developed. Thus, in the current chapter different techniques for collecting blood, bile and lymph samples are described. Methods for obtaining blood without anesthesia of the rat, as well as methods requiring anesthesia are explained. In addition, blood withdrawal by using long-term catheterization of blood vessels is described. Techniques of bile sample collection include catheterization of the common bile duct. Finally, techniques of lymph sample collection through catheterization of the thoracic lymph duct and mesenteric lymph duct are explained.