Human beta-calcitonin gene-related peptide (beta-hCGRP) was isolated and purified from spinal cord. The complete characterization of this material was based on definitive mass analysis by fast atom bombardment mass spectrometry together with gas phase sequencing. Combining these data we have characterized the structure of beta-hCGRP including the C-terminal sequence, the presence of the S-S bridge and of phenylalanineamide as the C-terminal amino acid, and fully confirmed the amino acid sequence predicted from the nucleotide analysis.