Objective To explore the method and outcome of knee resurfacing arthroplasty in treating late-staged diffuse pigmented villonodular synovitis (PVNS). Methods Between November 2002 and May 2009, 11 cases of late-staged diffuse PVNS were treated, including 3 males and 8 females with an average age of 51.2 years (range, 42-63 years). The diseaseduration was 2.5-10.0 years (mean, 5.2 years). Unilateral knee was involved in all patients, including 7 left knees and 4 right knees. Nine patients had a history of trauma and 2 cases had no obvious inducing factors. The range of motion was (90.1 ± 17.2)° and Hospital for Special Surgery Knee Score (HSS) was 68.9 ± 8.7. After synovectomy, knee resurfacing arthroplasty was performed in all patients. Results Superficial infection of the incision occurred in 1 case at 6 days postoperatively and was cured after debridement; other incisions healed by first intention. Limited flexion and extension, incomplete palsy of common peroneal nerve, and deep venous thrombosis occurred in 1 case respectively, and were cured or improved after symptomatic treatment. All the 11 cases were followed up 38 months on median (range, 13 to 102 months). Two cases developed chronic pain and were not given treatment. Recurrence occurred in 1 case 12 months postoperatively and recovered after synovectomy again. X-ray films showed no signs of loosening, sinking, and bone destruction. At last follow-up, the range of motion was (109.1 ± 18.6)° and HSS score was 86.7 ± 9.3, showing significant differences when compared with those before operation (P lt; 0.05). According to the HSS score system, the results were excellent in 6 cases, good in 3, fair in 1, bad in 1, and the excellent and good rate was 81.8%. Conclusion A combination of knee resurfacing arthroplasty and synovectomy for the treatment of late-staged diffuse PVNS is able to get a good cl inical results in restoration of function, improvememt of the l ife quality, and decrease of recurrence rate.