INTRODUCTION: Recently, results from the large, randomized study to prospectively evaluate reamed intramedullary nails in patients with tibial fractures (SPRINT) trial suggested a benefit for reamed intramedullary nail insertion in patients with closed tibial shaft fractures largely based on cost-neutral autodynamizations and a potential advantage for unreamed intramedullary nailing in open fractures. We performed an economic evaluation to compare resource use and effectiveness of reamed and unreamed intramedullary nailing using a cost-utility analysis. METHODS: We calculated quality-adjusted life years (QALYs) for each patient from a self-administered health utility index 3 questionnaire for the first 12 months following the intramedullary nailing. A convenience sample of 235 SPRINT patients provided data on costs associated with health care resource utilization. All costs are reported in Canadian dollars for the 2008 financial year. RESULTS: We found incremental effects of -0.017 (95% confidence interval [CI] -0.021-0.058) and -0.002 (95% CI -0.060-0.062) QALYs for patients treated with reamed compared with unreamed intramedullary nails in closed and open fractures, respectively. The incremental costs for reamed compared with unreamed intramedullary nailing were $51 Canadian dollars (95% CI -$2298-$2400) in closed tibial fractures and $2546 Canadian dollars (95%CI -$1773-$6864) in open tibial fractures. Unreamed nailing dominated reamed nailing for both closed and open tibial fractures; however, the cost and the utility results had high variability. CONCLUSION: Our economic analysis from a governmental perspective suggests small differences in both cost and effectiveness with large uncertainty between reamed and unreamed intramedullary nailing.