Abstract: OBJECTIVE: To investigate the acute toxicity and genetic toxicity of tributyltin methoxide (TBTMO). METHODS: A total of 110 Kunming mice were randomly divided into 11 groups，then treated orally with various doses of TBTMO (420，286，194，180，132，90，73，61，41.5 and 28 mg/kg) to perform acute toxicity test. A total of 50 Kunming mice were randomly divided into 5 groups (TBTMO 80，40，20 mg/kg，positive control and negative control). Positive control was treated for five consecutive days. Other four groups were treated for two days. These animals were killed 35 d later，and their bilateral epididymis were removed for sperm shape abnormality test. Another 50 Kunming mice were randomly divided into 5 groups and treated as above mentioned. The animals were killed 30 h after gavage with TBTMO，and their chest bone marrow fluid were obtained for bone marrow micronucleus test. Another 50 GFP transgenic mice were randomly divided into 5 groups and treated as above. The animals were killed and their spleen lymphocyte was used for hprt gene mutation test. Various doses of TBTMO (69.4，48.6，34.0，23.8，16.6 and 0 μg/ml) were used to treat Chinese hamster lung (CHL) cell for chromosome aberration test. Different doses of TBTMO (5×105，5×104，5×103，5×102，50，5，0.5，0.05，5×10-3，5×10-4 μg/dish) were used to deal with TA97，TA98，TA100，TA102 strains for Ames test. RESULTS: The LD50 of TBTMO in mice was 98 mg/kg. TBTMO could induce sperm abnormality in a dose-dependent manner (P＜0.05). The other four tests showed negative results. CONCLUSION: Under our experimental conditions，TBTMO was classified as moderately-toxic substance. It may produce genetic toxicity.

Key words: tributyltin methoxide, acute toxicity, genetic toxicity