The auditory cortex of the sloth was studied through evoked responses method with demonstration of two active areas beneath the supra-sylvian grouve. In A-I the latency of the beginning of the surface positive wave range from 19 to 25 ms, predominantly 20 ms, and in A-II, range from 27 to 35 ms, predominantly 30 ms. With deep barbiturate narcosis a long latency responses (65-110 ms for the beginning of the surface positive wave) was observed spreading over the anterior pole cortex. Interaction of a continuous sound with the evoked responses in A-I was also investigated. Evoked responses in A-I cortex could be obtained after 25 minutes of asphyxia produced by obstruction of the trachea.