OBJECTIVE To evaluate the acute toxicity of Carbosulfan to earthworm, Eisenia fetida in the artificial soil over a 14 d exposure period.METHODS Earthworms, Eisenia fetida used in this study and fed with the cattle manure once a week were raised at 20 ±2℃ under the continuous light condition.Toxicity test was conducted at the same condition as breeding condition.Five series of concentrations with 50.00, 75.00, 112.50, 168.75 and 253.13 mg·kg-1 , dry weight, which wereprepared by adding the solution of the test substance into the artificial soil directly.The artificial soil for culture was prepared by mixing sphagnum peat: kaolin clay: air-dried quartz sand (1∶2∶ 7) with moisture content was adjusted as about 35% and pH was adjusted to 6.0 ±0.5.Test animals with 300-600 mg of body weight (wet mass) were selected.Four replicates for each treated group were carried out and ten earthworms were used in each replicate.During the 14 d exposure, the mortality was assessed and symptoms of intoxication and distinct changes in behavior were also recorded at day 7 and 14.LC50 (50%lethal concentration) and its 95% confidence limits were estimated using probit analysis program.RESULTS During the test, it turns out that the environmental conditions which contain temperature, relative humidity and light intensity had all met the requirements in 14 d exposure.In this study, there was no lethal organism in the control group so that this test could be regarded to meet the condition for the validity of the test.Carbosulfan induced death of test organisms was in a dose-dependent manner.At day 14 the highest concentration causing no mortality was zero, and the lowest concentration causing 100 percent mortality was 253.13 mg· kg-1 , dry weight, respectively.Meanwhile, the adverse reactions in the live earthworms became much more obvious along with the concentration became higher, and the exposure time was extended.The main pathological symptoms and changes in behavior were as follows: the earthworm body became crimped, shorter, twist, adherence, and clitellum swelling, and moving slowly, and broken into sections.CONCLUSION With exposure to test substance Carbosulfan, the LC50-7 d was determined as 140.961 mg·kg-1, dry weight, and the LC50-14 d was 103.353 mg· kg-1,dry weight, the 95% confidence limits were 119.187-172.092 mg· kg-1 , dry weight, and 88.534-119.780 mg· kg-1, dry weight, respectively.