Abstract Arthroscopic synovectomy (ASS) of a rheumatoid knee is performed in cases of intractable synovitis. This spares the articular cartilage, and is an effective and simple treatment for chronic knee synovitis. This retrospective study was performed to evaluate the outcome of surgical arthroscopy, and study the clinical results in detail. A total of 160 knees, in 138 patients, were assessed after a mean follow-up of 35 months. There was a statistically significant improvement in pain, synovitis, and walking ability for at least 24 months after surgery. Based on the results of our study, age, duration of rheumatoid arthritis (RA), and erythrocyte sedimentation rate (ESR) and level of C-reactive protein (CRP) at surgery were not predictors of a poor long-term outcome of ASS. However, the clinical results correlated with the Lansbury index, loss of extension of the knee joint, a modified Larsen score, and the Larsen grade of the knee joint. Of the cases studied, total knee arthroplasty (TKA) was performed in 29 knee joints. We concluded that although ASS can reduce local inflammation and delay the need for definitive replacement surgery, patients over 60 years of age who show severe radiographic changes should undergo primary TKA.