A prospective study was undertaken to determine the value of scintigraphy in predicting nonunion or necrosis of the femoral head following femoral neck fractures. Scintigraphy was carried out in 49 patients before operation and in 37 one week after operation; in 18 it was done before and after operation. The uptake of isotope was estimated visually as either normal or reduced compared to the opposite side. All the patients were followed up for at least 2 years. The results indicate that pre-operative bone scintigraphy is useful in elderly patients to predict nonunion and necrosis, and therefore is recommended to select those patients who will benefit from primary arthroplasty instead of fixation of the fracture.