One hundred thirty-four acute unstable fractures of the tibia were treated with a reamed intramedullary nail with locking capabilities. There were 101 closed and 33 open fractures (20 Grade 1 fractures, 12 Grade 2 fractures, and 1 fracture from a gunshot wound). Patients were seen in followup for an average of 16 months after nailing. The time to fracture union averaged 28 weeks in closed fractures and 39 weeks in open fractures. Delayed union (> 6 months) developed in 14 fractures (8%): 11 closed (11%) and 3 open (9%) fractures. Eleven of the 14 delayed unions healed spontaneously, or after dynamization of statistically locked nails. Seven fractures (5%) were not healed by 9 months and were classified as nonunion (2 closed, 5 open). All fractures required major additional procedures to obtain union. Infection developed in 13 fractures (10%). In closed fractures, there were 2 superficial (2%) and 3 deep (3%) infections; in open fractures there was 1 superficial (3%) and 7 deep (21%) infections. The authors conclude that reamed intramedullary nails should be restricted to unstable, closed tibial shaft fractures. Its use in open fractures even on a delayed basis cannot be recommended because of unacceptably high infection rates.