Aim: To study an ankle swelling following a trivial trauma in a young female. Case Report: A 30 year old patient presented with pain and swelling in the right ankle following a trivial injury 4 months back. Radiograph showed soft tissue swelling and USG showed a cystic swelling over the flexor tendon. We did an excision biopsy and the histopathology report was consistent with Giant Cell Tumour of the tendon sheath. Discussion: Giant cell tumour of the tendon sheath is a benign tumour usually arising in the limbs. It occurs more commonly in the hand and rarely in the foot. Patients usually present to the hospital because of pain and swelling. The masses arising from the tendons are of soft tissue density and calcification is uncommon. GCT-TS is histologically similar to pigmented villonodularsynovitis as haemosiderin deposits and numerous macrophages are seen in both. Conclusion: Giant Cell Tumours of tendon sheath are similar to pigmented villo nodular synovitis (PVNS). They are the second most common benign tumor next to ganglions. The treatment is surgical excision of the mass.