Objective: To explore a economical and effective method for building lung tumor model induced by diethylstibes- trol (DES). Methods: The carcinogenic effect of neonatal mice treated by DES was studied. The newborn mice were divided into DES, Urethan (U) and U + DES groups. U group was given in 500 mg/kg dose by ip at postnatal 14 day, DES group was administered by ip at the 1 d, 8 d, 15 d in the dose of 1/7, 2/7 and 4/7 LD50 of the day when they were injected respectively for DES (l), DES (M), DES (H) groups. Until 26 weeks, they were anatomized and checked the formation of tumors. The organ index, tumor incidence ratio and mean number of tumors were calculated. Results: Lung tumors were apparently induced in tested neonatal mice. The incidence of lung tumor of DES (L, M, H) groups were 16.7%, 22.4% and 43.1% respectively, the U + DES (L, M, H) groups were 70.4%, 90.9% and 70.8% respectively, and the U group was 53.1%. The mean numbers of lung tumors of U + DES (L, M) groups were higher than those of the DES (L, M) groups respectively (P < 0.05). Conclusion: The higher ratio of lung tumor incidence had been induced by DES and U joined action to neonatal mice, which may be a useful and economical method to establish a lung tumor model induced by DES. Objective: To explore a economical and effective method for building lung tumor model induced by diethylstibestrol (DES). Methods: The carcinogenic effect of neonatal mice treated by DES was studied. The newborn mice were divided into DES, Urethan (U) and U + DES groups. U group was given in 500 mg / kg dose by ip at postnatal 14 day, DES group was administered by ip at the 1 d, 8 d, 15 d in the dose of 1/7, 2/7 and 4/7 LD50 of the day when they were injected respectively for DES (l), DES (M), DES (H) groups. Until 26 weeks, they were anatomized and checked the formation of tumors. The organ index, tumor incidence ratio Results: Lung tumors were apparently induced in neonatal mice. The incidence of lung tumor of DES (L, M, H) groups were 16.7%, 22.4% and 43.1% respectively, the U + DES (L, M, H) groups were 70.4%, 90.9% and 70.8% respectively, and the U group was 53.1%. The mean numbers of lung tumors of U + DES (L, M) groups were highe r than those of the DES (L, M) groups respectively (P <0.05). Conclusion: The higher ratio of lung tumor incidence had been induced by DES and U joined action to neonatal mice, which may be a useful and economical method to establish a lung tumor model induced by DES.