Root tear of the posterior horn of the medial meniscus can occur from trauma or chronic degeneration, leading to meniscus extrusion, articular cartilage loss, osteophyte formation, and medial joint space narrowing. It is common on middle age with or without minor trauma. We experienced a case of medial meniscus posterior horn root tear in 13 years old boy during baseball game. We performed 1 direct suture anchor repair for medial meniscus posterior horn root tear in adolescent and report clinical result.