The interfragmentary micromotions in seven osteotomized cadaveric femurs were measured by using of strain accelerometers to study the effect of mechanical vibration on them under plate fixation or intramedullary nailing. The results showed that this measurement method with accelerometers was considerably accurate. It was confirmed that mechanical vibration could induce interfragmentary micromotion under nailing, but not under plate fixation. The negative curvilinear coorelation was found between vibration frequency and micromotion. Therefore, the choice of suitable vibration frequency deserves further researches if mechanical vibration is considered to be used in clinical practive.