OBJECTIVE: To explore the anatomic feature and clinical application of the bone (periosteum) flap pedicled with upper muscular branches of lateral femoral muscle. METHODS: The anatomic features and distribution of upper muscular branches of lateral femoral muscle were observed in the lower extremities of 40 adult cadavers. From February 1989 to February 1999, 7 cases with bone defect or nonunion of upper part of femur were treated with transfer of bone (periosteum) flap pedicled with upper muscular branches of lateral femoral muscle. RESULTS: The upper muscular branches of lateral femoral muscle originated from the transversal branch of lateral circumflex femoral artery. The musculoperiosteal branch and periosteal branch were originated at 16.8 +/- 3.0 cm below the greater trochanter. The diameter and length of musculoperiosteal branch were 1.4 to 1.7 mm and 2.7 to 5.6 cm, those of the periosteal branch were 0.4 to 0.6 mm and 1.2 to 1.5 cm respectively. Bone union achieved in 10 to 18 weeks after operation in all 7 cases after 18 to 42 months follow-up. The motion of hip joint reached 180 degrees in 4 cases, 120 degrees in 2 cases and 65 degrees in 1 case. The donor area recovered well. CONCLUSION: The bone (periosteum) flap pedicled with upper muscular branches of lateral femoral muscle is an effective alternative for repairing the bone defect or nonunion of the upper or middle part of femur.