The nervous system of the lamprey has been appreciated by comparative neuroanatomists for nearly a century as a "prototype" for the brain and spinal cord of higher vertebrates. Only recently have neurophysiologists discovered the practical advantages of the lamprey brain and spinal cord, such as relative simplicity, survival in isolation, and the occurrence of large, visible, nerve cells and axons. During the past 15 yr rapid progress has been made in understanding the basic physiological, pharmacological, and ultrastructural properties of lamprey neurons and the organization of sensory and motor systems. Several types of neurons are now known in considerable detail and include the prominent Müller and Mauthner cells, respiratory and spinal motoneurons, giant interneurons, and sensory dorsal cells. Some of the important subjects for future research include the behavioral responses of adult lampreys to different modes of sensory stimulation, the neural control of feeding, and the changes which occur in the nervous system during metamorphosis.Key words: brain, lamprey, neurophysiology, respiration, spinal cord, swimming