The nervous and sensory systems of lampreys, hagfishes, the coelacanth, lungfishes, and the basal ray‐finned fishes, such as bichirs and reedfishes, paddlefishes and sturgeons, garfishes and bowfins, are reviewed and compared with closely related groups of “primitive” fishes. Anatomical, physiological, molecular, and behavioral data are discussed in relation to both ecological and phylogenetic relationships. In addition to overviews of their embryology, development, and gross anatomy, a functional classification of the cranial nerves is also presented. The peripheral and central components of the visual (including nonvisual photoreception), chemoreceptive (olfaction and gustation), octavolateralis (audition and lateral line), and electroreceptive systems are examined in some detail, highlighting the physiological basis for behavior wherever possible. Although a number of neuroanatomical, neurochemical, physiological, and molecular studies have greatly enhanced our understanding of brain evolution in these important groups, physiological studies are remarkably still scarce and need to be undertaken in order to trace the origins of craniate brains and the evolutionary constraints placed on neural plasticity and function.