Objective: To study the acute toxicity and inheritance toxicity of water extract of Cuscutae Semen in SD rats. Method: The acute toxicity of water extract of Cuscutae Semen in SD rats was detected by maximum tolerated dose method. Micronucleus test of pregnant mice bone narrow cells and fetal mice hepatocytes were carried out:5 groups were used for bone narrow and fetal hepatic cell

include high

middle and low dosage of water extract of Cuscutae Semen (40

20

10 g·kg-1

respectively)

negative control group (normal sodium

NS

10 mL·kg-1) and positive control group

the micronucleus rates of bone marrow and fetal hepatic cell were evaluated by micronucleus tests. Result: The maximum dosage of administration of water extract Cuscutae Semen was 80 g·kg-1. Compared with negative control group

the micronucleus rates of bone marrow and fetal hepatic cell were all significantly increased (P<0.01) at a high dose of 40 g·kg-1. Conclusion: The maximum tolerance dose of water extract of Cuscutae Semen (80 g·kg-1) in SD rats is belonged to the non-toxic substance. The high dosage of water extract of Cuscutae Semen (40 g·kg-1) has potential genetic toxicity on micronuclear rates of pregnant mice bone marrow cell and fetal mice hepatocytes

but middle and low dosage of it (20

10 g·kg-1) have no genetic toxicity.