Aortofemoral bypass is the operation we prefer in occlusive disease of the abdominal aorta and iliac arteries. The procedure is occasionally contraindicated by the patient's age, debility, or associated disease states. In such cases a less extensive bypass procedure may be of value. When the predominant lesion is a unilateral iliac artery obstruction, the opposite side being relatively normal, a crossover femoro-femoral bypass graft should be considered. We have used this form of bypass in this setting in poor risk patients with impending gangrene, rest pain, or early tissue compromise of a leg with gratifying results. The following reports describe six cases in which the operation was successful; the probable reasons for failure in two other cases are discussed. Report of Cases Case 1.—A 79-year-old white man was admitted to University Hospital in November 1966 because of gangrene of the left great toe. He had had intermittent claudication for several