The microscopic structure and ultrastructure of the eustachian tube(E-tube) was well known in guinea pig, chinchilla and mongolian gerbil but histologic study of the E-tube of rabbit has not been established. The aim of this study was to elucidate the microscopic morphology and ultrastructures of the E-tube of the New Zealand white rabbit and to prepare basic data on the characteristics of secretion and specific secretory site of surface tension lowering substance(STLS). Four types of epithelial cells, ie. ciliated, nonciliated, secretory cells and basal cells were found in the epithelium of New Zealand white rabbit E-tube. There seemed to be three different types of secretory cells, ie. dark granulated, light granulated and mixed cells. The substance which looked like the lamellar bodies were observed in-the secretory cells and in the lumen of the E-tube. The microscopic morphology and ultrastructure of the E-tube of the rabbit were almost identical with those of chinchilla, guinea pigs, human, etc.