The effect of pancuronium on induced hypotension by histamine and d-tubocurarine was investigated in the rabbit. The results are summarized as follows; 1) Intravenous diphenhydramine(5ug) pretreatment attenuated the arterial hypotension induced by 3ug of histamine and 30ug of d-tubocurarine. 2) Pancuronium in doses of 1ug, 3ug, 10ug and 30ug produced an attenuation of the vaso depressor action of histamine 3pg but was not does dependent and the depression rate was 20%, 25%, 24% and 49% respectively. 3) Pancuronium in dose of 0.3ug, lug, 3ug and 10ug produced to attenuate the vasode-pressor action of d-tubocurarine 30ug, which it was dose dependent attenuation of vasode-pressor action at dose from 0.3ug to 3ug and depression rate was 19%, 26%, 52% and 20% respectively.