Lipoma arborescence (LA) is a rare intraarticular lesion mostly seen in the knee joint. We present a case of a 72 year old man, who had a swelling of the right knee of 5 years duration. He had pain and restriction of motion when swelling occured. We performed an arthrotomy and synovectomy. Magnetic resonance imaging (MRI) and histopathologic examinations confirmed the diagnosis of LA. He had no swelling at the last control examination. His pain was reduced but continued because of osteoarthritis (OA). LA should be included in the differential diagnosis of the patients with recurrent effusions in patients with or without OA.