The presence of VIP-like immunoreactivity in human neuroblastoma cell line NB-1 was demonstrated by radioimmunoassay of the crude cell extract and by immunocytochemical staining of the cells. Gel filtration profiles of VIP-like immunoreactivity in the cell extract measured by radioimmunoassays using three different region-specific antisera revealed that the immunoreactivity consists of a major molecular form corresponding to porcine VIP having 28 amino acid residues with at least two additional minor forms larger and smaller than the VIP. In addition to VIP-like immunoreactivity, the cell extract was shown to contain substance P-, neurotensin- and somatostatin-like immunoreactivity as well.