To evaluate outcome after arthroscopic débridement, the records of 171 patients with osteoarthrosis of the knee were reviewed. All patients were unresponsive to conservative management and were treated arthroscopically. Procedures included lavage, meniscectomy, chondrectomy, removal of free bodies and removal of limited osteophytes. Outcome assessment was retrospective, evaluating the need for further surgery, control of pain, improved function and patient satisfaction. Sixty-five percent of patients felt their symptoms were improved. There was excellent control of pain in 38% and improved function in 22%. Subsequent surgical procedures were required in 12% at an average follow-up of 25 months. No factors were identified that correlated with the outcome, including the extent of degenerative changes and of débridement and patient profile. Arthroscopic débridement is a temporizing procedure with good patient satisfaction. Marked, but unpredictable, improvement in symptoms is seen in one patient out of three.