The locations of efferent auditory neurons in the white mouse were determined using retrograde transport of HRP from the cochlea. Labeled neurons were localized in the lateral superior olivary nucleus (LSO) and ventral nucleus of the trapezoid body (VNTB). The total number of efferent neurons was determined to be 475; of these 34.5% are medial group efferents and 65.4% are lateral group efferents. The ipsilateral LSO contains 99% of the lateral group neurons and the contralateral VNTB contains 75% of the medial group neurons.