By use of fluorescence immunohistochemistry it is shown that sciatic nerve section in cat and rat induces increased levels of immunoreactive calcitonin gene-related peptide (CGRP) in axotomized motoneurons. In the rat, this effect was clearly seen at 2-5 days postoperatively, but could not be demonstrated after 11-21 days. These findings are discussed in relation to previously proposed roles for CGRP in motoneurons.