A patient is reported who developed a fistula between the hip and the caecum 39 years after arthrodesis of her hip. She presented with a painful right hip and radiographs showed that the Smith-Petersen nail used for arthrodesis had moved up through the acetabulum and into the pelvic cavity. The nail was removed but within a week a fistula which discharged alimentary contents had developed between the hip and the caecum. The patient was treated conservatively, and three weeks later the fistula had closed.