Primary culture cells from eight cases of ameloblastoma were obtained and observed by means of light microscopy. Cells in four cases were observed by means of electron microscopy. Cultured cells in all cases resembled epithelial cells with the cells from follicular ameloblastoma more tightly packed than those from the plexiform types. Ultrastructurally, cells from follicular ameloblastoma contained many lysosomes, whereas cells from the plexiform type contained many vacuoles.