Brine shrimp toxicity of water extracts of twenty three crude drugs was tested by the brine shrimp bioassay. Eight crude drugs were shown to have 100% mortality in $1000{;}{mu}g/ml$. They were fractionated by Amberlite XAD-2 column chromatography and were tested by the brine shrimp bioassay. Methanol fraction of Rhei Rhizoma $(LC_{50}=49.60{;}{mu}g/ml)$ and Cantharis $(LC_{50}=54.08{;}{mu}g/ml)$ were shown to have potent brine shrimp toxicity in this test.