A simplified method for recording the cerebrospinal fluid pressure in the dog is presented. It consists of introducing the polyethylene tube of a Rochester needle into the sub-arachnoid space at the level of the ventral atlanto-occipital joint. The advantages of this technique are: the dura mater is punctured under direct vision; a completely sealed fluid system results which permits direct inspection for cerebrospinal fluid leakage; and the animal may be placed in any anatomical position during the continuous monitoring of cerebrospinal fluid pressure. This method of measuring the cerebrospinal fluid pressure has been utilized in 30 canine experiments and has proven equally effective in recording cerebrospinal fluid pressures in monkeys. Submitted on December 21, 1962