In femorsl neck fracture, viability of the femoral head depends on the revascularization of the femoral head. The purpose of this study is to observe the effect of early fixation and anatomical reduction by measuring the Tc-99m-MDP uptake ratio of the femoral head in experimental animsls. Femoral neck region of 20 mature rabbits were osteotomized completely and divided into 2 groups ; each group consisted of 10 rsbbits. Group 1 had two Kirschner wire fixation after osteotomy and anatomic reduction. Group 2 had no fixation after osteotomy. The uptake ratio of Tc-99m-MDP of the femoral head in each group were measured st the intervals of 24 hours, 48 hours, 1 week, 2 weeks, 3 weeks, and 4 weeks, respectively. The results obtained were as follows ; 1. In experimental group 1, the mean uptake ratio of the femoral head was 0.72±0.13 at 1 day after operation, increased to a level of 1.44±0.14 at 1 week, increased to a maximal value of 2. 90±0.36 at 3 weeks and decreased to a level of 1.10+0.12 at 4 weeks. 2. In experimental group 2, the mean uptake ratio of the femoral head was 0.70±0.10 at 1 day, 0.64±0.13 at 1 week, decreased to a maximal value of 0.33±0.05 at 3 weeks and 0.47±0.05 at 4 weeks, showing decreased level below 1.0. The results suggest that early anatomicsl reduction and rigid fixation of femoral neck fracture is helpful for revascularization of the femoral head and prevention of non union.