Anxiety, depression and anger are feelings that the cancer patient cannot avoid. Sometimes anxiety develops into panic. This report is of a severe case of panic disorder that developed after an operation for gastric cancer. A 40-year-old woman was admitted in May, 1984,with recurrent panic attacks which had begun one month earlier. Two months before admission, she had a total gastrectomy for advanced gastric cancer. Her early postoperative course was uneventful. However several days after the operation she developed a panic attack with nausea and vomiting during the course of a drip infusion of antineoplastic drugs. The attack subsided immediately after discontinuation of the infusion. Two weeks later a panic attack appeared again during another course of intravenous antineoplastics. Except for short term interval, attacks persisted for the next month prior to her admission to our hospital. Physical examination revealed tachypnea, tachycardia and emaciation. The patient was in distress from fits of crying and chest discomfort. Even having a meal or passing urine could easily bring about panic with hyperpnea, which persisted in duration from 20 minutes to several hours. Arterial gas analysis showed no abnormalities. She was dependent, aggressive and regressive. She was not informed of the diagnosis, but she seemed to be aware of it following the operation and the administration of antineoplastics, and as a result she went into a state of panic. She was extremely afraid of the radiographic examination of the upper gastro-intestinal tract and of the drip infusion, though she denied fear of death or cancer. Tranquilizers or antidepressants had little effect on attacks, and training in abdominal breathing, hypnotherapy or behavioral therapy were also in vain. We diligently supported the patient to try to enable her to cope with anxiety and to release emotions with her family and friends. The patient was discharged in July, 1985,because attacks decreased in frequency. She had never experienced a day free from attacks until May, 1986,when panic attacks suddenly subsided. Thereafter she has had no relapse for this three year period and has adapted well to society. To our knowledge, panic disorder following an operation for gastric cancer has not been previously reported in medical literature. An interesting feature of this case was that panic attacks were in hyperpnea without hypocapnia and they were quite severe in frequency and duration, but they did eventually subside.