A new cell line (YKK) was established from a primary tumor of neuroendocrine carcinoma of the endometrium. Cultured YKK cells are polygonal in shape. The modal chromosome number is 46 XX. The doubling time of the cells, after the 19th passage, is 38 hours and this cell line has been propagated continuously by serial passage over 50 passages for the past 2 years. YKK displays characteristics resembling the original tumor cell from the donor patient: it contains the neuron-specific enolase and chromogranin antibody, produces neuron-specific enolase, and is sensitive to cisplatin, carboplatin, and etoposide. When YKK cells are transplanted subcutaneously together with Matrigel into nude mice they form a very large tumor invading the subcutaneous muscular tissue. This experimental model is useful for studying the mechanism(s) regulating the invasion of this tumor into muscular tissue, and for the establishment of new anti-cancer treatments for neuroendocrine carcinoma.