Abstract: The phenomenon of brassinosteroid (BS) on rice laminae inclination was demonstrated to be epinasty. Elongation in the upper side of the treated pulvinus was more rapid than elongation in the lower side. The effect of BS on rice laminae inclination was hardly reversed. BS-induced epinasty appeared to be due to stimulation of ethylene production, because the inhibition of ethylene by CoCL2 also inhibited epinasty.