402 consecutive patients with various disorders of digestive tract were investigated concerning heartburn and 184 cases (45%) proved to have heartburn. No significant relationship was established between the heartburn and gastric acidity or the kinds of digestive diseases. Heartburn was not only seen in hyperacidity but also often seen in hyp-and anacidity or normacidity. No significant correlation was observed between the heartburn and the rate of emptying the gastric content. Flow back of bile in stomach juice was relatively often seen in cholecystopathic patients with heartburn, but no such relationship was proved in other kinds of patients. Experimentally beartburn was evoked in the patients with heartburn by administration of 30 cc of 1% sodium bicarbonate solution in the stomach or ten cc in oesophagus, but not by the same quantity of hydrochloric acid (N/20), lactic acid (N/20), 10% syrup, 50% polytamine solution, physiological saline, or 5% bile dilution. A habit of eating fast was observed relatively often in heartburn patient. Profession of the most of the above examined patients was farmer and they noted some causative relation to large intake of food rich in carbohydrate (sweetpotato, rice-cake, etc. ). The most frequent time for heartburn to beginn was one to three hours after a meal.