Purpose: To identify the damage of the articular cartilage and analyze the clinical results of the partial medial meniscectomy. Materials and Methods: From January 2001 to December 2004, forty-eight patients in the degenerative arthritis and medial meniscal tear of knee who undertook arthroscopic partial meniscectomy and were able to keep pace with the times follow-up for more than 3 years were enrolled in this study. Six cases were men and 42 were women, and the mean age was 55.7 years (40~78 years). The patients were classified into two groups according to the Outerbridge grade. Grade I and II were classified into group 1 and grade III and IV into group 2. Group 1 included 30 cases and group 2 included 18 cases. The result were analyzed according to the Tapper & Hoover classification and Lysholm knee scoring scale. And we measured the distance of medial joint space in standing anteroposterior (AP) view of both sides at the pre-operative and the last follow-up. Results: According to the Tapper & Hoover classification, 28 cases were excellent, 7 cases good, 8 cases fair, and 5 cases poor. Among group 1, 25 cases were excellent, 2 cases good, 2 cases fair, 1 case poor. However, among group 2, 3 cases were excellent, 5 cases good, 6 cases fair, 4 cases poor. Average Lysholm knee score was improved from 62.4 preoperatively to 94 postoperatively in group 1, and from 58 preoperatively to 77.9 postoperatively in group 2. The joint space narrowing showed no statistically significant difference in both knees standing AP view. Conclusion: The arthroscopic partial meniscectomy for a patient with the degenerative articular cartilage was an effective treatment. However, we could not satisfy the results, in cases of Outerbridge grade III and IV. In grade III and IV, the partial meniscectomy was not aggravated the cartilage damage.