In 20 cats (2.5-3.4 kg) anesthetized with intraperitoneal Dial (allobarbital) (1.55 cc/kg), the medulla was explored from 2 mm rostral to 10 mm caudal to the obex with 2 [mu] micropipette electrodes for single units firing synchronously with a phase of respiration. The distribution of units firing during each phase of respiration has been mapped and found to conflict with previous maps determined by different methods.