Forty-three vascularized iliac crest grafts in the femoral neck region in 38 patients were assessed with marrow scintigraphy. Twenty grafting procedures had been performed for treatment of fractures, 16 for nontraumatic osteonecrosis, and seven for focal bone lesions. Scintiscans were obtained preoperatively and in the early and late postoperative period. Anterior images of the hips were obtained 30 minutes after intravenous injection of 4 mCi (148 MBq) of technetium-99m tin colloid by using a gamma camera with a low-energy, general-purpose collimator. The viable graft was detected as an area of tracer uptake corresponding to the configuration of the graft on radiographs. Marrow scintigraphy at 12 weeks showed that 24 grafts were viable, 11 were nonviable, and eight were indeterminate. Early and late results concurred in 36 of 43 (84%) grafts. Nonviable grafts occurred most frequently in fractures in the elderly. In seven patients who subsequently required total hip replacement, six grafts were nonviable while one was indeterminate at 12 weeks. Results indicate that marrow scintigraphy is useful in the treatment of patients with vascularized iliac crest bone grafts.