This paper is aimed to study the incidence, age and sex distribution, and type of lateral meniscal lesion including discoid meniscus in Korea. It is reported higher incidence of lateral meniscal lesion in Korea. 132 cases with meniscal lesions were surgically treated at the Department of Orthopedic Surgery, Seoul National University Hospital between 1973 and 1982. Of the 98 patients who had lateral meniscal lesions, forty-four (44.9%) were found to have a discoid meniscus. The mean age of the patients with discoid meniscus was 17.9 years, and 30 patients of them were younger than 20 years of age. The patients with discoid meniscus were followed after meniscectomy for an average of 6 months. The summary of this study are as follows: l. Over-all incidence of discoid meniscus were 44 cases (33.3%) out of 132 cases of the meniscal disease. All forty-four cases had a lateral discoid meniscus, and they formed 44.9% among 98 cases of lateral meniscal injury. 2. The discoid meniscus was most frequent in the age group between 11 and 20 years old (65.9%), and was more prevalent in female by a ratio of 1.4. 3. Qf the 26 patients with torn discoid meniscus, twelve (46.2%) denied the history of trauma. 4. Symptom of click sound was present in 42 cases (95.5%), and the rate of positive McMurray sign was 81.8%.