Abstract Background: Medial gonarthrosis is a joint disease that causes knee pain, reduction of activity and progressive alteration of the medial compartment, mainly in elderly and fat people (1). Medial opening wedge high tibial osteotomy (MOWHTO) is an established procedure in the treatment of patients with medial compartmental osteoarthritis (2). The aim of our study was to assess the early results of medial open wedge osteotomy in medial uni-compartment OA fixed with a plate. Patients & methods: Patients included in this study were 25 patients. The minimum follow up of patients was 6 months. The patients mean age was 47 years, ranging from 36 to 59 years. All the patients were suffering from medial uni-compartmental osteoarthritis of knee joint. They treated with an oblique medial opening wedge high tibial osteotomy and fixation by using a plate. Result: All the patients were evaluated at the end of the study regarding their function demand and they were further graded according to their satisfaction. A total of 15 patients (60%) reported the procedure as excellent; eight patients (32%) much better and two patients (8%) little better. The mean correction angle was 9.6 degrees. Full weight-bearing was achieved after an average of ten weeks (range: 8-12 weeks). Superficial infection, deep infection, skin irritation, and cutaneous saphenous nerve hyposensitivity were complications occurred in the patients of the study group. The mean preoperative Oxford knee score (OKS) was 20; while the mean postoperative oxford knee score (OKS) was 37. Conclusion: Medial opening wedge high tibial osteotomy (MOWHTO) fixed with a plate is a physiologically better surgery in primary medial compartment OA of the knee in early stages. The procedure is a very good alternative to unicompartmental or total knee arthroplasty. Early results are very gratifying. However, achieving successful outcomes requires proper patient selection, effective planning, meticulous surgical techniques, and good rehabilitative programs.