The histomorphological influences of ovariectomies and estradiol injections on the nasal mucosa were observed in adult female guinea pigs. In the mucosa of ovariectomized guinea pigs, degenerative changes including dissolving and desquamation of cilia and glandular hypotrophy were found. On the contrary, thickening layer of the epithelium, spongiosis and edema of the corium, hyperplasia of glands and increased density of cilia were observed in the mucosa of guinea pigs receiving estrogen. The results demonstrated that different levels of estrogen might have different effects on the nasal mucosa.