A 45-year-old Chinese man presented with recurrent bilateral knee swelling and pain. He was initially diagnosed with gouty arthritis, but later found to have lipoma arborescens. Magnetic resonance imaging demonstrated frond-like proliferations of fatty synovium. Arthroscopic synovectomy was performed. Histological examination of the specimen revealed villiform fatty tissue covered by slightly thickened synovium characteristic of lipoma arborescens. Magnetic resonance imaging is useful in differentiating lipoma arborescens from other intra-articular lesions in patients with recurrent knee pain and swelling.