We have described a technique for rapid serial blood sampling and intravenous injections via the jugular vein in the rat. The animal, without any prior preparation, is restrained on a specially designed board. Entrance into the vein is made cephalad to the pectoralis muscle. A trained technician can bleed 40 rats weighing 100 to 600 g in 1 hr. Considerable time is saved by using plastic syringes to collect the blood so that no transfers of samples are necessary for processing.