Calcitonin gene-related peptide(CGRP) is a peptide that is made during alternative mRNA processing of primary transcripts of the calcitonin gene. The presence of CGRP has been demonstrated in a variety of central and peripheral neurons by immunocytochemistry, raidoimmunoassay, and chromatography. The distribution of CGRP fibers suggests that CGRP may take part in sensory transmission. The olivocochear bundle originates from the superior olivary complex and is compsed of crossed and uncrossed fibers. The lateral system orginates form the lateral superior olivary uncleus, and the medial system orginates from the medial and ventral nuclei of the trapezoid body and periolivary nuclei. The purpose of this study was to observe the CGRP distribution of rat brain stem, using indirect immunofluorescent and immunoperoxidase technique. We demonstrated a more extensive network of CGRP like immunreactive fibers distributed in various areas throughout the rat brainstem, at light microscope level using immunofluorescence and immunopoxidase technique. CGRP-like immunoreactivities were shown in the cochlear nucleus and lateral superior olivary nucleus(LSO). The location of CGRP-labelled neuron and nerve fiber confine to the lateral olivocochlear system.