The purpose of this study was to review the operative long-term results of a large cohort of children treated arthroscopically for a symptomatic discoid lateral meniscus. We retrospectively reviewed the arthroscopic procedures performed on 104 knees (97 patients) between 1990 and 2006 to treat symptomatic discoid lateral meniscus in children. The median age at the time of surgery was 8 years (range 2.5-13.9 years). The follow-up was 8.5 ± 2.5 (mean ± SD) years (median 9, range 2-18.5 years). In this series, young children (2-7 years) usually presented complete discoid menisci with deficit in extension and little pain. The meniscal tissue was almost degenerated, and subtotal meniscectomy was performed. Children aged from 8 to 14 years referred to our institute typically presented a symptomatic tear (pain and swelling joint with snap) of a complete or incomplete discoid lateral meniscus, usually pursuant to a trauma. The treatment performed in this group was a partial meniscectomy. Clinical results at long-term follow-up show better results for subtotal meniscectomies than for partial ones. The results showed the long-term efficacy of arthroscopic treatment of a symptomatic discoid lateral meniscus. On the basis of this study, subtotal meniscectomies in younger patients are preferable when meniscal tissue is degenerated. In older children, we recommend to preserve meniscal tissue as much as possible. In younger patients submitted to subtotal meniscectomies, some adaptation of the knee to stress activity may occur. Therapeutic case series, Level IV.