The aim of this retrospective study was to determine the short-term effects of proximal femoral derotation osteotomy (FDO) on gait in 53 ambulatory patients with spastic diplegia controlling all confounding procedures. All patients showed a jump gait pattern and had undergone bilateral rectus femoris transfer, distal hamstring lengthening, and tendo-Achilles lengthening as a single-event multilevel surgery. Of these, additional bilateral proximal FDOs were included in 25 patients, defined as the FDO group; the other 28 patients were defined as the no-FDO group. Kinematic variables, such as pelvic tilt, minimal hip flexion in stance, hip rotation, and foot progression angle, were compared between the two groups at postoperative 1 year. Hip extension, hip rotation, and hip adduction improved significantly after surgery in the FDO group (P<0.001, P=0.004, P=0.028), but not in the no-FDO group. Foot progression angle improved in both groups, but the degree of improvement was significantly greater in the FDO group (P=0.004). In conclusion, FDO improved hip rotation, hip adduction, and hip extension as well as foot progression angle in the ambulatory patients with spastic diplegia showing a jump gait.