Clinical experiences of 35 cardiothoracic operations in Jehovah's Witness patients were presented with special reference to a method of taking informed consent for surgery. At first the surgeon explained the details of the proposed surgery including its risks and benefits. He should also express his confidence in accomplishing the operation without blood transfusion. Otherwise he should not dare to perform the operation. The surgeon asked the patient to talk about his or her religious belief in transfusion denial. Then the surgeon was allowed to talk about his professional duty and ethical belief in saving the patient at all costs. Finally, both the patient and the surgeon would sign the document of informed consent without fully determining whether or not the patient would undergo transfusion at an unexpected situation since the possibility of such unexpected necessity of blood transfusion was believed extremely low by both the surgeon and the patient. The trust of the patient in the technique of the surgeon was the key to this agreement.