Schizophrenic patients, whether newly admitted to hospital or institutionalized, exhibited ear differences in absolute threshold. Right ear thresholds were superior to left ear thresholds especially at frequencies above 2 kHz, but deteriorated in the course of the day or as a result of repeated testing. These effects were attributed to the dynamics of left hemisphere processes which in schizophrenia appear susceptible to inhibition and fatigue, effects that may be endocrine related. Relative to control subjects institutionalized schizophrenic patients showed superior hearing below 1 kHz and inferior hearing above 2 kHz.