In children, snapping knee syndrome and joint pain with the loss of physiological hyperextension strongly suggests a diagnosis of a torn discoid meniscus. We performed arthroscopic meniscectomy to treat torn discoid lateral meniscus on 19 knees and open meniscectomy on 9 knees of 26 children(average age: 10.9 yrs) from September, 1983 to October, 1993 at Guro hospital. According to Ikeuchi's grading system', excellent results were obtained in 14, good in 11, fair in 2 knees and poor in 1 knee which was associated with osteochondritis dissecans. The knees treated by partial meniscectomy showed less Fairbank's radiologic changes than those by total meniscectomy during the average follow-up 4.2 years(minimum 1 year, maximum 7 year 11 months).