Introduction. Acetylsalicylic acid ingestion may cause serious gastrointestinal toxicity, in particular bleeding or perforated peptic ulcer. Case Outline. A 72-year-old male patient presented with diffuse abdominal pain, malaise, and dark stools. Several days before hospitalization, he had cerebrovascular insult and began to use acetylsalicylic acid of 100 mg per day. In physical findings a diffusely painful sensitivity of the abdomen was detected on palpation. Laboratory findings revealed hyposideremic anaemia with inflammatory syndrome. Native abdominal x-ray did not show the presence of pneumoperitoneum. Upper endoscopy of the gastric corpus and antrum revealed several ulcerations 10-11 mm in diameter covered with fibrin, with bleeding ulceration in the angulus region of the lesser gastric curvature. The bulbus was oedematous and hyperaemic with a perforated ulcer on the anterior wall. Upper central laparotomy showed a perforated duodenal bulbus. The posterior wall of the bulbus was normal, while the anterior wall was without scarring. Given the general condition of the patient and local findings, interrupted suture of the ulcer was performed with omentoplasty. Postoperative course was uneventful. A peroral diet was initiated on the 4th postoperative day, and the patient was discharged on the 8th postoperative day. Conclusion. Elderly people who use acetylsalicylic acid in prophylaxis should take it in lower doses, with proton pump inhibitors, especially during the first two months.