The effects of Lipoid of Mujingzi〔LP,Fruits of vitex neguando L Var cannabifo- lia (Sieb et Zucc) Hand mazz〕 on Smooth muscles are reported. The results were as follows:① In the isolated perfused mice lung-bronchi, LP caused significant increase of perfusion medium dropping through the lung-trachea, and the effect of LP was dose-dependent; ACh (Acetyl-choline)-induced contraction of the isolated mice trachea smooth muscles could be relaxed by LP. ② When LP was given introperitoneally(100~ 300 mg?kg-1) into guinea pig, the incubationperiod of asthma induced by acetycholine together with histamine was prolonged.The optimum dilated effect of LP on smooth muscles of trachea in mice can be concluded as the results of synergistic effects by 4 compositions from LP (Oleic acid,Linoleic acid, Palmitic acid and Stearic acid).