1. A series of twenty-one cases of re-fracture of the femoral shaft has been examined and analysed.

2. Liability to re-fracture may be increased if the original injury is caused by great violence, but it does not seem to be affected by the method of primary treatment.

3. Over 60 per cent of the re-fractures were avoidable. In some, re-fracture was caused by premature institution of vigorous mobilisation; in others, warning cracks were visible on radiographs before re-fracture.

4. In the remaining patients re-fracture appears to be unpredictable and unavoidable.

5. Re-fracture is best treated by the simplest methods.