Three cases of melanocytic tumors arising in the sympathetic chain were studied. A metastasis from one of them was studied with electron microscopy. Both light and electron microscopy demonstrated the presence in these tumors of true melanogenesis and autophagic activity in melanocytes as well as phagocytosis of mature melanin by associated histiocytes. Review of the embryology, biochemistry and in vitro culture of sympathetic nervous tissue showed a close relationship between it and pigmented cells in other parts of the body which are also derived from neural crest. These findings support the clinical and morphological conclusion that these rare pigmented tumors are true melanocytic tumors originating from the sympathetic chain. The malignant potential of these tumors is emphasized by the fact that the two patients who survived initial surgery later died of metastatic disease.