1. The age of the patient has no influence on the incidence of non-union in fractures of the forearm in adults.

2. The degree of displacement of the fracture is an important factor in non-union, and is related to the violence of the injury.

3. Fractures of one bone unite better than fractures of both bones, and this is due to the stabilising effect of the intact bone.

4. Open and comminuted fractures have a much higher incidence of non-union.

5. The lowest incidence of non-union, allowances being made for other significant factors, was in cases treated conservatively; and after that in cases treated by plating followed by immobilisation in plaster.

6. Plating without subsequent immobilisation in plaster is a method to be abandoned, but there is some advantage in waiting for ten days, until post-operative oedema has been absorbed, before applying the plaster.

7. In cases in which several factors predisposing to non-union are present in the same patient, it seems justifiable to supplement plating by cancellous onlay strips as a primary procedure.

8. In cases of non-union the cancellous insert graft described by Nicoll succeeded in 94·5 per cent of the cases, many of which were exceptionally difficult problems. In 75 per cent union occurred within four months of grafting.

9. The restoration of mobility, either after union of the fracture or after grafting operations, was never a serious problem in the present series.