1. A method is described for determining the presence or absence of a circulation within the femoral head after fracture of the neck of the femur.

2. An account is given of the fate of nineteen femoral heads in patients who had sustained high femoral neck fracture and in whom these tests had been carried out.

3. A favourable prognosis as regards fracture union and viability of the head was found to be correct in twelve of fifteen patients.

4. Non-union and major collapse of the head occurred in four patients in whom a diagnosis of an anaemic head had been made.

5. The morbidity of the method is described.

6. An explanation is given why vascular assay has been carried out as a secondary procedure, and possible clinical applications are indicated.