For many years, a perforated ulcer of the stomach and duodenum was recognized only at autopsy or during laparotomy for acute peritonitis. With the accumulation of experience and clinical observations, ulcer perforation began to be recognized before surgery. Further improvement of diagnostics allowed to perform surgical interventions at an earlier date. The data of the combined statistics convincingly speak about the improvement in the diagnosis of perforated ulcers and the timing of the delivery of patients to surgical institutions. If before the revolution only 12% of patients were admitted in the first 6 hours from the onset of perforation, in recent years the number of patients admitted to surgical institutions in the first 6 hours has increased to 53.1% and significantly decreased in the later stages. If before the revolution 28.2% of patients were admitted later than 24 hours, now 8.3% of patients are admitted within these terms. But this figure should be considered large. We must ensure that all patients with perforated ulcers are delivered to surgical facilities no later than 6-12 hours from the onset of perforation. Our current capabilities (annual increase in the number of doctors, ambulance stations and providing them with the necessary number of cars, air ambulances) make it possible to ensure the admission of patients with acute diseases, including those with a perforated ulcer, in the first 6 hours. During the post -war years, 71.5% of patients are hospitalized in our clinic in the first 6 hours from the onset of perforation. Many authors indicate that when referring patients to surgical hospitals, the attending physicians do not always determine the correct diagnosis. Our team statistics show that out of 1315 patients, only 532 (40.5%) were admitted to the clinic with a diagnosis of perforated ulcer; 215 people (16.3%) were admitted with an indication in the direction of “acute abdomen”; 60 (4.5%) – “exacerbation of gastric ulcer”; 172 (13%) – “acute appendicitis”; 156 (11%)—no diagnosis indicated. The rest were sent with diagnoses: peritonitis, cholecystitis, food poisoning, gastritis, etc. This suggests that the health authorities still have a lot to do to improve the skills of doctors at polyclinics and health centers. With the perforation of the ulcer, the contents of the stomach, including gastric juice containing hydrochloric acid, pour into the abdominal cavity, which causes sudden severe pain in the abdomen, i.e., a condition called “acute abdomen” occurs. Perforation often occurs with a full stomach. Some patients begin to drink heavily to quench their thirst. In this regard, the contents of the stomach continue to flow into the abdominal cavity, which increases pain and accelerates the development of the inflammatory process, i.e., peritonitis. Thus, during the perforation of the ulcer, two periods are observed: the first – “acute abdomen” and the second – peritonitis. Of course, it is impossible to precisely establish the boundary between these periods, just as one should not imagine that one is a continuation of the other. The development of peritonitis begins from the moment of perforation, but its full clinical manifestation occurs after some time, which depends on the amount and nature of the outflowing contents, on the number and type of microbes that have entered the abdominal cavity. In view of the exceptional importance of establishing a diagnosis of a perforated ulcer in the first 6 hours from the onset of perforation, when presenting the symptoms, we will talk about those that are characteristic of the first period.