Sixteen patients with infected total knee arthroplasties (4 postoperative and 12 late hematogenous) were treated by arthroscopic irrigation and débridement. All patients had < or = 7 days of knee symptoms, and there were no radiographic signs of osteitis or prosthetic loosening. Six of the 16 original total knee arthroplasties (38%) did not need prosthesis removal at a mean follow-up of 64 months (range, 36-151 months). Ten other knees were treated with irrigation, débridement, and hardware removal within 7 weeks of the latest procedure used to try to retain components. Two (13%) of these cases ultimately required an arthrodesis for persistent infection. Although we still believe that this method is preferable to resorting immediately to implant removal for acute infections, arthroscopic débridement was less efficacious for most situations when compared with open treatment. We would use arthroscopic irrigation and débridement only under selected circumstances (medically unstable or anticoagulated patients).