AIM The relaxing effect of the extract from Schizophyllum commune (SC) on rat aorta as well as the underlying mechanisms were investigated.METHODS Dried SC was extracted with 50%, 90% ethanol or deionized water.After the administration of SC, the isometric tension was measured in rat aortic rings with or without endothelium.RESULTS In endothelium-intact or in endothelium-denuded rat aortic rings, the water extract of SC induced significant relaxations, which were markedly decreased by the pretreatments of L-NAME, indomethacin, RP-cAMP, methylene blue and high concentration of KC1.In Ca2 +-free solution, incubation of the aortic tings with SC significantly inhibited the Ca2 +-dependent contraction.CONCLUSION The water extract of SC induces an endothelium-dependent and-independent relaxation in rat aorta.The activations of NO-cGMP, PGI2-cAMP pathways and K +channels, and the inhibitions of Ca2 + channels may be involved in the vasorelaxing effect of SC.