Thirty-five humeral shaft non-unions treated by the Ilizarov external fixator were studied after an average of 39 months. Bone union was achieved in all but one. The mean time to union was 5.5 months (range: 3-10 months). Major pin tract problems leading to removal of the Schanz screws occurred in three patients. A. radial nerve palsy developed in three patients, two recovered spontaneously and one was treated with a triple tendon transfer.