The ultrastructures of the uncinate processes (UP) obtainel from 16 patients with clinical diagnosis of chronic sinusitis were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that there were three main surface cell types on the UP: Most of the cilia was leaned, fractured and in disorder; Gaps of the cells increased obviously; Squamous cell metaplasia was seen; The endoplasmic reticulums and mitochondria in cytoplasm were expanded moderatly or seriously. The morphological changes indicated that mucus transportation functions in the anterior ethmoid region and the middle meatus were damaged. It is of great importance in occurrence and development of chronic sinusitis. The demaged nasal mucosa epithlial cells are repairable and reproducible.