The lipoma arborescent of the knee consists of a benign villonodular proliferation of fat under the synovial membrane. It is a rare entity often secondary to previous trauma. Hoffa's fat is an extrasynovial intracapsular fat pad that which looks like a quadrangular pyramid is in the anterior-inferior compartment of the knee joint. The case of a 44-year-old male patient is presented, professional trainer, who complains of pain and increased volume of the anterolateral region of the right knee. Arborescent lipoma of Hoffa's fat is diagnosed. Key words: lipoma arborescent, Hoffa fat, knee lipoma, benign Hoffa fat tumor