Relative 2-deoxyglucose (2-DG) uptake was investigated during pentobarbital and/or ketamine anesthesia, when animals were either kept in silence or stimulated with wide band noise at 85 dB SPL. In the absence of anesthesia, noise stimulation produced a large increase in relative 2-DG uptake, when compared to silence, in all auditory nuclei up to and including the inferior colliculus. Much more modest noise-induced increases were seen in the medial geniculate nucleus and auditory cortex. These effects were markedly altered by anesthesia. Pentobarbital, and especially pentobarbital plus ketamine, enhanced stimulus-evoked increases in relative 2-DG uptake in lower auditory nuclei: the cochlear nuclei, superior olivary complex and ventral nucleus of the lateral lemniscus. At the same time, stimulus-evoked increases were decreased in the dorsal nucleus of the lateral lemniscus and inferior colliculus, and virtually eliminated in the medial geniculate and auditory cortex. The results of this study permit more meaningful comparison of 2-DG techniques with electrophysiological measures of central auditory activity, and illuminate the utility and limitations of each method. The data indicate that 2-DG observations from barbiturate-anesthetized preparations should be interpreted with some caution. They further suggest that the 2-DG technique is inappropriate for the study of stimulus-evoked activity in the medial geniculate and auditory cortex of barbiturate-anesthetized animals.