The records of fifty-one patients who were treated by intramedullary nailing with reaming for non-union of the tibia were retrospectively reviewed. The fractures had been treated initially by closed reduction and immobilization in a cast, external fixation followed by immobilization in a cast, fixation by pins incorporated in a plaster cast, minimum internal fixation and immobilization in a cast, dynamic compression plating, or intramedullary nailing with or without reaming. After the initial treatment had failed, intramedullary nailing with reaming was done to gain union. Although closed nailing of the tibia was preferred, in thirty-three patients, the site of the non-union was opened to improve alignment by performing an osteotomy or to remove failed hardware. Bone grafts from the iliac crest were used in ten patients, and a fibular ostectomy or osteotomy was done in thirty-three. Of thirty-four open fractures (fourteen grade I, seven grade II, and thirteen grade III), eight were infected at the time of intramedullary nailing. The average time of the diagnosis of a non-union was 9.6 months; the average length of follow-up after nailing was twenty months. In forty-nine (96 per cent) of the fifty-one patients, tibial union occurred at an average of seven months postoperatively. Complications included persistent infection (three patients), acquired infection after intramedullary nailing with reaming (three patients), fracture of the nail that necessitated an additional operation (two patients), shortening of more than one centimeter (two patients), malrotation of more than 15 degrees (one patient), peroneal palsy (one patient), and amputation (one patient). When used to treat non-union of the tibia, intramedullary nailing with reaming can produce union as effectively as other alternatives, while enabling the patient to function more normally without external immobilization or walking aids.