Introduction. Giant cell tumor of bones is an uncommon neoplasm that accounts for 5% of all primary tumors of bone, and it represents about 9% of malignant primary bone tumors with grades from borderline to high grade Case Report: A 34–year–old patient came with complains of mild pain in right knee since 6 months when she came for generalized body checkup. On examination,no swelling was present over the proximal and anterior part of proximal leg and movements of knee joint were normal. All routine blood investigations were done and found to be normal. X–ray and CT knee showed morphology of defined lytic lesions with lobulated margins, very thin sclerotic rim,multiple internal septations,, ground glass density, internal calcifications seen in the epi–metaphyseal region of the right proximal tibia. The lesion is located eccentrically below and lateral tibia intercondylar region and right lateral tibial condyle. Mild endosteal scalloping of the lateral border with no cortical breach and periosteal reaction at the right proximal tibia suggestive of giant cell tumor. Histopathology of the tissue shows multinucleated giant cells with uniform vesicular nucleus and mononuclear cells which are spindle shaped with uniform vesicular nucleus suggestive of chondromyxoid fibroma a varient of GCT. The patient was treated by excision, curettage, bone cement and bone graft to fill the defect. Conclusion. The patient at 2–month followup is doing well and walking without any pain comfortably and with full range of motion at knee joint with articular congruity of knee maintained and no signs of recurrences.