A case of fatal metastatic melanoma arising from a very large congenital melanocytic naevus (VLCMN) is reported. Large congenital naevi (LCMN) are naevi >20 cm in diameter. VLCMN is used in this report to mean an extensive LCMN involving a large percentage of the body, including smaller so-called satellite naevi. A 19-year-old man with a large congenital melanocytic naevus (LCMN) presented with a new nodule on the left chest wall, which was diagnosed as a thick melanoma with synchronous axillary lymph-node metastasis. The patient developed widespread distant metastasis within weeks after surgical resection of the primary site and lymph-node basin, which was unresponsive to systemic chemotherapy and whole brain radiation therapy, and he died 7 months after diagnosis of the primary melanoma.