The aim of this paper is to investigate whether human nasal epithelial cells can differentiate into ciiated cells and secretory cells simultaneously by the floating method. Dissociated human nasal epithelial cells from nasal polyp were cultured in Ham's F12-Dulbecco's modified Eagle medium 1/1 Supplemented with 10% NU serum, choleratoxin, retinoic acid and antibiotics. We observed the morphologic changes after floating by the tranaission electron microscope. Electron lucent cornified cells in upper layer and flat cells in basal layer were noted at the time of confluence. Two to three layers of the cuboidal cells which mean some differentiation of squamous-like cells were observed 4 day after floating. Seven days after floating, the progression of cell differentiation by observing more number of cilia produced along with ciliated epithelial cells was noted. Electron dense secretory granules were located near the nucleus and electron lucent secretory granules were located eear the secretory cell membrane. Fourteen days after floating, completely differentiated ciliated epithelial cells and the cells which has electron lucent secretory granules were observed. Our results shows that the squamous-like cells can be differentiated into ciliated and secretory cells simultaneously by the floating method.