BACKGROUND In the emergency department pain in the right lower quadrant is a frequent finding and is related to a wide variety of diseases, the most common of which is acute appendicitis. An unusual presentation of pain in the right iliac fossa is due to perforation of a duodenal peptic ulcer. The fluid that originates from the perforated ulcer moves through the paracolic sulcus to the right iliac fossa and causes irritation of the peritoneum and even chemical peri-appendicitis, thereby imitating all the usual causes of pain in the right lower quadrant. This condition is known as Valentino's syndrome, named after the Italian actor Rudolph Valentino. CASE REPORT The aim of this case report was to review the current published literature regarding Valentino's syndrome and report on a case involving a 51-year-old male who was admitted to our surgical department with right lower quadrant pain and suspicion of acute appendicitis. An exploratory laparotomy was performed, from which a retroperitoneal perforation of a duodenal ulcer was found; suture closure was then applied. The patient's postoperative course was uncomplicated, and he was discharged 9 days after the operation. CONCLUSIONS Surgeons should be alert for this rare condition imitating acute appendicitis, and the differential diagnosis of right lower quadrant pain should include peptic ulcer perforation.