Ninety-one patients who had ninety-four open fractures of the tibial shaft were randomized into two treatment groups. Fifty fractures (nine type-I, eighteen type-II, sixteen type-IIIA, and seven type-IIIB fractures, according to the classification of Gustilo et al.) were treated with nailing after reaming, and forty-four fractures (five type-I, sixteen type-II, nineteen type-IIIA, and four type-IIIB fractures) were treated with nailing without reaming. The average diameter of the nail was 11.5 millimeters (range, nine to fourteen millimeters) in the group treated with reaming and 9.2 millimeters (range, eight to ten millimeters) in the group treated without reaming.Follow-up information was adequate for forty-five patients (forty-seven fractures) who had been managed with reaming and forty patients (forty-one fractures) who had been managed without reaming. No clinically important differences were found between the two groups with regard to the technical aspects of the procedure or the rate of early postoperative complications. The average time to union was thirty weeks (range, thirteen to seventy-two weeks) in the group treated with reaming and twenty-nine weeks (range, thirteen to fifty weeks) in the group treated without reaming. Four (9 per cent) of the fractures treated with reaming and five (12 per cent) of the fractures treated without reaming did not unite (p = 0.73). There were two infections in the group treated with reaming and one in the group treated without reaming. Significantly more screws broke in the group treated without reaming (twelve; 29 per cent) than in the group treated with reaming (four; 9 per cent) (p = 0.014). There was no difference between the two groups with regard to the frequency of broken nails (two nails that had been inserted after reaming broke, compared with one that had been inserted without reaming).The functional outcome, in terms of pain in the knee, range of motion, return to work, and recreational activity, did not differ significantly between the groups.We concluded that the clinical and radiographic results of nailing after reaming are similar to those of nailing without reaming for fixation of open fractures of the tibial shaft, although more screws broke when reaming had not been done.