Endothelin‐converting enzyme is a phosphoramidon‐sensitive metalloprotease that cleaves big endothelin to the potent vasoconstrictor peptide, endothelin. The converting enzyme is expressed in endothelial cells in a variety of tissues and in some secretory cells. In the present study, phosphoramidon‐sensitive endothelin‐converting enzyme activity has been demonstrated by radioimmunoassay in the neuroblastoma cell line, SH‐SY5Y, and in Bu17 and C6 glioma lines. The identity of the activity was confirmed by immunoblotting, revealing a polypeptide of ∼120 kDa in each of these lines, in D384 glioma cells, and in primary astrocytes. Immunofluorescence revealed the cell‐surface location of endothelin‐converting enzyme in the neuronal and glial cell lines and in primary astrocytes. Pretreatment of SH‐SY5Y and Bu17 cells with phosphoramidon resulted in an apparent concentration of the enzyme protein in an intracellular compartment. Immunoperoxidase‐staining of rat brain sections located this metalloprotease to the pyramidal cells of the hippocampus. Endothelin‐converting enzyme‐1 was revealed by in situ hybridisation in the neuronal and glial cell lines.