Using an antibody against GABA, neurons within the guinea pig hindbrain, midbrain and forebrain auditory nuclei were identified which demonstrate GABA-like immunoreactivity. GABA-positive cells were localized in the cochlear nucleus, superior olivary complex, lateral lemniscus, inferior colliculus, and medial geniculate body. GABA-positive terminals could be seen surrounding globular and spherical cells in ventral cochlear nucleus and principal cells in medial nucleus of the trapezoid body. In addition, numerous positive, punctate terminals appeared throughout the hindbrain auditory nuclei and, although fewer in number, in midbrain and forebrain auditory nuclei.