A 19-year-old man was evaluated for medial knee pain 1.5 year after repeated distortion of the right knee. The medial side of his knee was swollen and painful upon running and playing soccer. An anteroposterior knee radiograph showed a calcification located at the proximal medial collateral ligament. He was diagnosed with Pellegrini-Stieda syndrome. Treatment of this syndrome includes rest, range of motion exercises, nonsteroidal anti-inflammatory drugs, local infiltration with corticosteroids or excision in refractory cases. Diagnosis: Pellegrini-Stieda syndrome.