The rat tail vascularization is histologically re-examined especially with respect to blood sampling and vascular-injection methods. The terminal third of the tail is recommended for blood vessel puncturing. In this segment, the arteries and veins are most prominent, since the structures of the musculo-skeletal system diminish towards the tip of the tail. In addition to the commonly-known blood vessels (one ventral artery, two lateral veins), there is a dorsal vein in the rat tail that is well suited for puncture and cannulation.