BACKGROUND There is no consensus as to which is best treatment of femoral fractures in children. METHODS We performed a cost analysis comparing three treatments of femoral shaft fractures in children aged 3-15 years at 3 hospitals during the same period (1993-2000). The analysis included total medical costs and costs for the care provider and were calculated from the time of injury up to 1 year. RESULTS At hospital 1, treatment consisted of external fixation and early mobilization. At hospital 2, the treatment was skin or skeletal traction in hospital for 1-2 weeks, followed by home traction. At hospital 3, treatment was skin or skeletal traction in hospital until the fracture healed. RESULTS The average total costs per patient were EUR 10,000 at hospital 1, EUR 23,000 at hospital 2, and EUR 38,000 at hospital 3. CONCLUSIONS The main factor for determining the cost of treatment was the number of days in hospital, which was lower in children treated with external fixation.