Purpose To examine the complications of arthroscopic knee surgeries conducted in the Sports Medicine and Knee Center of our hospital. Subjects and methods In this prospective study, a total of 2,623 patients (1,396 men and 1,227 women) who underwent arthroscopic knee surgeries in our center between January 2006 and March 2013 (7 years and 3 months) were studied. The ages at surgery ranged 7-96 years (mean 33.5 years). Arthroscopy was conducted because of sports injuries in 1,653 patients (63.0 %). The main diagnoses included meniscal injury in 920 patients, discoid meniscus in 64 patients, anterior cruciate ligament injury in 580 knees, posterior cruciate ligament injury in 30 knees, loose body in 61 knees, and intraarticular fracture in 33 knees. Arthroscopic procedures included meniscectomy in 987 knees, meniscal suture repair in 262 knees, and anterior cruciate ligament reconstruction in 508 knees. Intraoperative and postoperative complications in these cases were investigated. Results The rate of complication was 7 in 2,623 cases (0.27 %). Intraoperative complications comprised three cases of intraarticular instrument breakage and one case of meniscal injury. Postoperative complications consisted of two cases of septic arthritis and one case of superficial infection, and reoperation was necessary in the two cases of septic arthritis. There were no neural, vascular and ligament injuries during surgery, and no complex regional pain syndrome, symptomatic deep vein thrombosis, and pulmonary embolism were observed. Conclusion Arthroscopic knee surgeries are considered to be minimally invasive, and are conducted relatively safe with low complication rates. In this series, however, seven cases of complications occurred, including two cases (0.08 %) of septic arthritis. Furthermore, symptomatic thromboembolism has been reported to occur also in arthroscopic surgery. The risk of severe complications has to be acknowledged.