Two months after total endoprosthesis of the hip (Spotorno) a 60-year-old obese female patient complained about increasing hip pain. Costly diagnostic measures could not clarify the cause. Analgesic therapy administered with local cortisone injections was not satisfactory. Upon deterioration of her general condition the patient was hospitalized. A periprosthetic abscess of the hip with atypical muscle necrosis could not be controlled after several interventions. Computed tomography of the abdomen and hip revealed a jejunoacetabular fistula after mesenteric perforation with small intestine diverticulosis. It seems to be the first published case. After abdominal and hip surgery the further course was good. There was no need to replace the prosthesis. Retroperitoneal abscess with purely coxal symptomatology has been described. Diverticulitis of the small intestine has a poor prognosis. When infections with unusual necrosis resistant to therapy after hip prosthesis surgery occur, consideration must be given to retroperitoneal abscess. Abdominal tomography allows the life-saving surgery.