It is very rare to see medial discoid meniscus, and there have been only 82 knees in 61 cases reported to date. The investigators found discoid medial meniscus with horizontal cleavage tear in a 13-year-old juvenile who had been injured while playing basketball, and endured for 3 years. Both magnetic resonance images and the arthroscopic findings were presented. Saucerization of the torn discoid medial meniscus was performed successfully, and the clinical outcomes were satisfying according to the follow-up of 14 months.