BACKGROUND: Valentino’s syndrome is secondary to a perforated peptic ulcer, which could be located in the stomach or the duodenum, patients present with clinical features that suggest acute appendicitis, with localized peritonitis. There are few case reports about this syndrome worldwide and no one submitted in Ecuador. It is essential to transmit this clinical case for the knowledge of the medical- scientific community. CASE REPORT: A 63-year-old male patient came to the emergency department with abdominal pain, located in the right iliac fossa, that began 12 hours ago, associated to peritoneal irritation signs and hemodynamic decompensation; suggestive of peritonitis. An exploratory laparotomy was performed. EVOLUTION: During exploratory laparotomy, no inflammatory changes were identified in the appendix. After abdominal cavity exploration, a perforated gastric ulcer was found. Primary raffia was stitched in two planes, incidental appendectomy and lavage of the abdominal cavity were performed. The patient had a successful recovery; and was discharged after 7 days at hospitalization. CONCLUSION: The perforation of a peptic ulcer can generate right iliac fossa pain, simulating acute appendicitis due to its clinical similarity. The medical team should consider Valentino’s Syndrome as an important differential diagnosis during the evaluation of a patient that arrives to the emergency room with abdominal pain, suggestive of appendicitis. KEYWORDS: ABDOMINAL PAIN, ILIUM, APPENDICITIS, PEPTIC ULCER PERFORATION, ABDOMEN ACU-TE, PERITONITIS