Among 280 patients with femoral neck fractures 46 were classified as having impacted fractures according to the criteria mentioned below. The treatment of patients with impacted femoral neck fractures was determined to be mobilization with partial weight-bearing from the first day of admission. Among the 42 patients successful in immediate mobilization there were eight whose fractures disimpacted. Three cases of avascular necrosis were recorded but no cases of non-union. In order to determine the predictive signs of secondary dislocation the X-ray findings were subjected to statistical analysis. The inclination of the fracture line, dislocation into a valgus or varus position and the presence of retroversion did not influence the tendency to disimpaction. More than 80 per cent of the fractures healed without disimpaction.