Abstract: The occurrence of calcitonin gene-related peptide(CGRP)and its mRNA was studied in lungs of Macaca mulatta using ABC-GDN immunohistochemistry and in situ hybridization.The results demonstrated that CGRP was located in neuroendocrine cells (NEC) and neuroepithelial bodies (NEB),including all airways from bronchi,bronchioles and alveolar ducts.The distribution of CGRP hybridization positive cells was similar to that previously discribed with immunohistochemistry.Labelling for CGRP mRNA was evenly distributed over the cytoplasm,whereas CGRP was usually of high intensity toward the base of neuroendocrine cells,suggesting basal accumulation of synthesized peptide.The nerve fibers in walls of the intrapulmonary bronchi and blood vessels were also CGRP positive.Adjacent sections immunostained with antibodies to CGRP and 5-hydroxytryptamin (5-HT) proved the coexistance of CGRP and 5-HT in NEC and NEB.This finding suggests the possibility of functional interaction of CGRP with 5-HT.