We report on a case of an atypically located gallstone ileus as a rare complication of cholecystolithiasis. A 61-year old lady with a history of diabetes type II and nephrolitiasis presented with abdominal pain lasting for 8 days and with vomiting and diarrhoea. Physical examination revealed a palpable tumour and pain in the left lower abdomen. An extensive elevation of blood sugar, CRP and leukocytosis was found. Initially X-ray of the abdomen and sonography showed signs of a subileus. Additionally a 5 x 2 cm mass with dorsal shadowing was detected by ultrasound. Gallbladder and the biliary system were normal. The sonographic suspicion of a gallstone ileus was confirmed by a subsequent CT scan. Under operation the gallstone was found in the distal Jejunum. A gallstone ileus must be included in the differential diagnosis of a tumour in the left lower abdomen. A tumour with dorsal shadowing and signs of a subileus may be the only sonographic findings of a gallstone ileus.