The article describes the world's first documented case of acute inflammation of the gallbladder (cholecystitis) strangulating in an umbilical hernia. The patient was a 97-year-old woman with repeated problems with gallstones in the biliary tract, who presented with pain in the middle part of the abdomen and an irreducible, painful mass around the navel. Abdominal CT initially indicated a strangulated intestinal loop, and therefore urgent surgery was indicated. During the laparotomy, it was found that the acutely inflamed gallbladder was strangulated in the umbilical hernia, and at the same time the common bile duct was significantly dilated up to 2 cm. Surgeons performed a gallbladder removal (cholecystectomy) and common bile duct exploration, where they found a 2 cm non-obstructing stone at the ampulla of Vater, which they successfully removed, and placed a T-drain to drain the bile. The abdominal wall was closed primarily, the patient was discharged on the 14th postoperative day in good condition, and the follow-up examinations were without problems. The main finding is that even very rare contents of a hernia, such as the gallbladder, can cause diagnostic difficulties and require an individually selected surgical solution.