(1) Fractures in the region of the neck of the femur are usually subdivided into the intra- and extra-capsular variety. This classification is faulty and misleading.(2) An analysis of the injuries, in the region examined in this series, shows them to be readily classifiable into five types. Although certain authors have attempted to subdivide the trochanteric variety into two, I am of the opinion that this is not practicable, since a large proportion are true neither to the intertrochanteric nor to the pertrochanteric type.(3) Since the great majority, at least, of the trochanteric fractures would, according to the older classification, have been called “extra-capsular,” and since it is stated that this type occurs generally in muscular adults and infrequently in old age, the large proportion found in this series directly contradicts the modern teaching.(4) It is submitted that even trochanteric (the so-called extra-capsular) fractures are not due to direct external violence in the aged. The suggested mechanism can be regarded as a compression action of the affected limb, resulting when the whole weight of the body is suddenly thrown upon it. The bone breaks in the vicinity of its angle (the region of the intertrochanteric line), and not through its weakest point, the neck.(5) The transcervical, and presumably also the subcapital fractures, are caused by an axial torsion of the cervix femoris.(6) In the trochanteric fractures there is usually impaction of the upper fragment into the lower. Sometimes, in addition, the great trochanter is comminuted, but more commonly the small trochanter, with or without a thin portion of the shaft, is chiselled off by the most inferior part of the upper fragment, which almost invariably has a sharp lower angle.(7) The subtrochanteric fracture is in reality a fracture of the shaft proper. It involves the inferior portion of the trochanter major. There appears to be no definite agreement about the trauma producing it.(8) “Avulsion fractures” of the trochanter major consist of the detachment of the tip of that prominence, presumably as a result of spasmodic muscular action.(9) The degree of shortening of the limb varies considerably in the first three varieties discussed, and it is no criterion, clinically, of the type which has occurred.(10) The fracture most frequent in the aged is that through the mass of the trochanter major, and X-ray examination alone reveals the nature and extent of the damage.