Pigmented villonodular synovitis (PVNS) is a rare disease that has clinical and histopathological characteristics of both benign proliferative disorder and a chronic inflammatory process of the synovial tissue. The primary mode of treatment is surgery followed by an adjuvant radiotherapy; however, the risk of recurrence is a significant (40-70%). Several publications suggest that the TNF-α inhibitors might be a treatment option. We present a case of a 29-year-old female diagnosed with PVNS of the knee joint, refractory to surgery and 3 radionuclide synovectomies. Because the possibilities of conventional therapy were exhausted, treatment with an intra-articular anti-TNF-α monoclonal antibody (infliximab) was performed. Despite a high safety profile and a good tolerance of that therapy we did not observe significant clinical and radiological improvement. To assess the effectiveness of intra-articular TNF-α inhibitors as an adjuvant treatment in PVNS, prospective studies are needed.