Objective To determine the effect of non-reamed versus reamed intramedullary nailing for tibial fractures in adults on the rates of nonunion, the rates of implant failure, the rates of infection, the incidence of compartment syndrome, the rates of malunion, and the time of union. Methods We searched MEDLINE （1966 -July, 2005）, EMBASE （1974 -July, 2005 ）, The Cochrane Library （Issue 2, 2005 ）and CBMdisc （1979 -July, 2005 ）, and handsearched the relevant Chinese and English orthopedic journals. Randomized controlled trials and Clinical controlled trials of nonreamed versus reamed intramedullary nailing for tibial fractures in adults were included. The quality of trials was critically assessed. RevMan 4.2.7 software was used for data analysis. Results Four RCTs and one CCT of non-reamed versus reamed intramedullary nailing for tibial fractures in adults were included. The results of meta-analysis showed that nonreamed intramedullary nailing for tibial fractures in adult increased the rates of nonunion （RR 1.87, 95% CI 1.20 to 2. 91, P =0. 006）, implant failure （RR 2.23, 95% CI 1.49 to 3.34, P〈0. 000 1 ） and the time to union （WMD 9.00, 95% CI 3.19 to 14.81, P =0. 002）. Conclusions Compared with reamed intramedullary nailing for tibial fractures in adults, non-reamed intramedullary nailing increases the rates of nonunion and implant failure is common. There is no statistical difference in the rates of post operative infection, the rates of malunited fracture and the incidence of compartment syndrome between the two groups. However, further studies are needed to determine the effects of reamed and non-reamed intramedullary nailing on these outcomes, expecially when patient has severe open fractures （Gustilo Grade Ⅲ C）and multiple injuries.