TO reveal the kind of information about the larynx which is transmitted to the central nervous system during vocalization, we studied discharge patterns of single fibers of the laryngeal afferent nerve during electrically induced vocalization in ketamine-anesthetized cats. Recorded fibers were classified into four types based on their discharge patterns. Type A fibers responded to vocal fold vibration during vocalization. Type B fibers increased their activity during vocalization without synchronization with vocal fold vibration. Type C fibers decreased their activity during vocalization. Type D fibers discharged only at the onset of vocal fold adduction and abduction. We discuss the functional properties of these afferents and the possibility that these afferent inputs participate in the feedback control of vocalization.