High tibial osteotomy is preferential treatment for patients with knee osteoarthritis. Strengthening exercise program helps post (HTO) patients achieve greater functioning during sport, recreation, and activities of daily living after surgery. To examine the effect of postoperative exercise program on knee physical function among high tibial osteotomy patients. Method: quasi experimental research design. Department of Orthopedic Surgery and orthopedic Outpatient Clinic at Assiut University Hospital.A purposive sample of 60 adult patients undergoing high tibial osteotomy were included in our study. Knee Outcome Survey Activities of Daily Living Scale and Lysholm knee scoring scale were used.  A highly statistically significant improvement of knee Function score and Lysholm knee score (<0.001**) among patients with high tibial osteotomy.!Application of exercise program had a statistically significant effect on improvement physical function of knee among the study group than among the control group.  Successful postoperative exercises should be practiced for each patient undergoing high tibial osteotomy in order to improving physical function of the knee.