The authors have observed a case o hemangioendothelioma occurred on the left palate and buccal mucosa of a 40 year old woman. The results are as follows. 1) A blue-red round mass, 1.0cm in diameter, appeared on the palate and a blueviolet oval mass, 1.2cm in diamcter, on he buccal mucosa, and both of them showed a tendency to bleed after even slight trauma. 2) Microscopically the lesion was composed predominantly of masses of endothelial cells proliferating in and about the undifferentiated vascular channels. 3) well-vascularized tissue was made up of vascular spaces, showing infilitration of small round cells.