Introduction: Gastric bypass is one of the strategies that have shown better results in the management of obesity, since this technique is the one that strikes a better balance between risk, side effects and long-term results. It consists in the creation of a gastric reservoir that anastomosis to the jejunum, reducing the size of the gastric chamber and thus the patient tolerates less food and decreasing its intake. One of the less frequent late complications is duodenal perforation. For this reason, we present this case report, according to the CARE guideline. Case presentation: 47-year-old male patient with a history of gastric bypass due to obesity, who consults for sudden onset of abdominal pain. Physical examination showed signs of peritoneal irritation and systemic inflammatory response. Exploratory laparoscopy was performed with suspected hollow viscus perforation, hich evidenced a 1 cm ulcer on the anterior aspect of the duodenal bulb, requiring omentoplasty by aparotomy. Conclusions: Perforated duodenal ulcer in patients with a history of gastric bypass is a rare diagnosis. It has a non-specific clinical presentation, which is why exploratory laparoscopy is considered a valid diagnostic and herapeutic strategy.