Transection experiments establish that the mechanisms responsible for the generation of the basic breathing pattern are located in the medulla. Several populations of neurons with activity patterns related to this motor pattern are readily recorded in the medulla, and much information has been obtained in the past 10 years about the physiology of these medullary respiratory neurons and their possible interconnections, inputs, and interactions. This evidence does not support the hypothesis that the basic alternations between expiration and inspiration is the result of a stable oscillatory network containing only the presently known medullary respiratory neurons. It is proposed that conventional extracellular recording methods have missed important parts of the medullary respiratory mechanism.