Objective To investigate the treatment and therapeutic efficacy of intra-articular meniscal cysts by arthroscopy. Methods From January 2005 to December 2009, 9 cases of intra-articular meniscal cysts were treated by arthroscopy, including 5 males and 4 females, with an average age of 33.8 years (range, 24-46 years). Six patients suffered in left knees, 3 in right ones. Just 1 case had trauma history, the others had no obvious predisposing causes. The average course of the disease was 24.2 months (range, 4-36 months). The Lysholm score was (74.2 ± 11.6) points. Arthroscopy showed that the locations of cysts were the anterior horn of lateral meniscus in 8 cases and the anterior horn of medial meniscus in 1 case; all being single cyst (of them, 3 being multilocular cyst). Results All incisions healed primarily with no compl ications of infection and joint effusion. All 9 patients were followed up from 3 to 48 months with an average of 12.7 months. Preoperative symptoms disappeared or reduced and the range of motion of the knee returned to normal. TheLysholm score was (95.1 ± 3.4) points after 3 months of operation, showing significant difference (P lt; 0.01) when compared with the socre before operation. According to assessment standard described by Choy, the treatment outcome was excellent in 6 cases, good in 2 cases, and general in 1 case; the excellent and good rate was 88.9%. No recurrence was found during follow-up. Conclusion Arthroscopic surgery shows the advantages to maintain good function of knee for the treatment of meniscal cyst, it is the best choice for intra-articular meniscal cysts because of its mini-trauma, rapid recovery, thorough treatment and less recurrence. Simultaneously, partial or tatol meniscectomy or menicus repairing under arthroscopy is performed.