Introduction Gallstone ileus is a complete or partial mechanical bowel obstruction due to gallstone impaction in the bowel lumen and most commonly occurs after stones migrate through the cholecystoenteric fistula. Case outline We present a patient with signs of gallstone ileus after stone migration through the cholecystoduodenal fistula into the duodenum with hematemesis as the first symptom. Conservative treatment had been started, to which the patient initially responded well. On the eighth day from the onset of the disease, the condition worsened. Signs of the Rigler triad were identified on computed tomography and magnetic resonance imaging of the abdomen. Enterolithotomy was successfully performed by the open surgical method. Postoperative recovery was orderly, without any biliary problems. Conclusion Physical examination, upper endoscopy, and radiological diagnostic procedures are complementary and necessary in monitoring the dynamics of stone movement and deciding on when to perform surgery.