Sixty-eight closed tibial shaft fractures were treated with an anterior unilateral external fixator over a 5 year period (1986-1991). Pin tract drainage and/or infection was seen in 71/380 pins. The total number of secondary operations, excluding planned pin extraction, during fracture healing was 61 (including 22 due to pin tract problems and 25 secondary corrections of alignment). Delayed union was seen in 14 fractures and non-union in three. Healing disturbances were more frequent following high-energy trauma. Bone grafting was done in 11 fractures. Eventually, all fractures healed within an average of 22 weeks. There were three refractures. At follow-up, on average 3 years after injury, functional results were excellent in 41 per cent, good in 46 and acceptable in 13 per cent. Due to the high number of unplanned secondary operations and prolonged healing times we do not consider the use of unilateral external fixation to be an adequate method for the treatment of closed tibial shaft fractures. The poor results are probably due to weight-bearing being too high in these patients relative to the mechanical stability provided by the external fixator system.