Abstract: The toxicity of sediment and water of Suzhou Creek was investigated by toxicological methods including acute and sub-acute toxicity test performed on luminescent bacteria, fishes, mice and rats. In luminescent bacteria toxicity test, for the reaches of Zhaotun, Huangdu, Huacao, Beixinjing, Panwanli,
Changshou Lu Bridge, Wuning Lu Bridge and Zhejiang Lu Bridge, exposure to the water and the lixivium of sediment inhibited the luminescence, which suggests these samples have toxicity effect on the photobacteria. Furthermore, the toxicity effect is more obvious in urban reaches than in suburb ones, in summer than in winter, in the sediment than in the water. In field test, for the reaches of Changshou Lu Bridge and Zhejiang Lu Bridge, after exposure for 96 hours the livability rate of crucian respectively decreased to 0% and 30%;but for Huangdu reach the livability rates crucian was 83 %. The results suggest urban reaches are evidently unsuitable for cruciads survival. The results of the test on mice suggest the sedimant of Beixinjing
reach has acute toxicity to mice. According to the results of sub-acute test on rats the sediment and the water of Beixinjing reach could be harmful to animars liver. On the basis of the above results we draw the conclusion that Suzhou Creek especially its reaches in urban area is unfavorable for biological survival.

Key words: sediment, water, toxicity, Suzhou creek, sediment, water, toxicity