The addictive effects by pancuronium on relaxation response to ether, methoxyflurane. halothane, trilene and enfluranc were investigated in the isolated rat intestine preparation. The following results were obtained. 1) Ether in doses of 0.03cc/30ml, 0.1cc/30ml and 0.3cc/30ml produced dose dependent relaxation. 2) Methoxyflurane, halothane, trilene and enflurane in doses of 0.03 cc/30ml, 0.1/30ml and 0.3 cc/30ml did not produce dose dependent relaxation. 3) In the presence of pancuronium in doses of 1 mug/ml and 3mug/ml, ether produced marked dose dependent relaxation respectively in comparison with ether administration alone. 4) In the presence of pancuronium in doses of 1 mug/ml and 3 mug/ml, methoxyflurane, halothane, trilene and enflurane did not produce dose dependent relaxation respectively.