[en] An experimental model of normal human respiratory tract (NHRT) using xenotransplanted human fetal tracheobronchial segments (HFTBs) was established for study of toxic effects and/or carcinogenesis by ¹⁴⁷Pm. Flat ¹⁴⁷Pm metal β source was cut into a 10 x 8 mm² rectangle, rolled up into a cylinder (length 10 mm, outer diameter 2.55 mm) and then put into the lumen of HFTBs which has been grafted for 2 months. According to the thickness of gold foil covering the source and HFTBs' tissues irradiated by β emitters from ¹⁴⁷Pm, the dose rate of irradiation was calculated to be 2.82 Gy/hour. Extensive hyperplasia of epithelium appeared in the early stage and squamous multistep are major lesions at 4 weeks after irradiation. The experimental results show that NHRT is useful and has unique advantages as compared with other experimental models in study of toxicology and carcinogenesis of radiation