The pathogenesis of the nasal polyp is multifactorial and choanal polyps can be defined by its origin of genesis: antrochoanal (maxillochoanal), ethmochoanal and sphenochoanal polyp. Transforming growth factor-β (TGF-β) has various biologic activities, including the regulation of epithelial proliferation, the promotion of extracellular matrix formation and the induction of angiogenesis, hence closely related to pathogenesis of nasal polyp. Twenty cases of choanal polyps (13 antrochoanal, 4 ethmochoanal and 3 sphenochoanal polyps) were included in this study. Each polyp was subdivided into its origin, pedicle and choanal part. Hematoxylin and eosin stain for routine histopathology and immunohistochemistry were employed to detect expression of TGF-β1. According to polyp type, edematous type is common at origin part and fibrous type at choanal part, and showed no difference at pedicle part in frequency. In ethmochoanal and sphenochoanal polyps, glandulocystic and edematous type is more common than fibrous type. TGF-β1 was expressed in epithelial cells, endothelial cells, eosinophils and lymphocytes. There was no different expression of TGF-β1 in each kind of choanal polyps and separate parts in each polyp. But histologic finding of choanal polyp is different between origin, pedicle and choanal part. Also infiltration of inflammatory cells including eosinophils has no difference between origin site. The expression of TGF- β1 was observed at all the choanal polyps and no difference between origin site and each portions was noted.