The form of onset of undifferentiated spondyloarthropathies varies widely among individuals. There is an acute onset as well as an insidious onset. Symptoms include joint manifestations and extra-articular manifestations, and complications mainly include spondyloarthropathies and ankylosing spondylitis. 1. Joint manifestations (1) The first symptom may be arthritis, or inflammatory low back pain or hip pain, mostly with heel pain as the first manifestation, and some patients have recurrent iritis before arthritis attack. (2) Patients with arthritis are mostly monoarticular or oligoarticular, asymmetric, with the knee, ankle and foot joints of the lower limbs being the most common. Occasionally, the disease starts in the wrist joint with joint stiffness and swelling, and large amounts of inflammatory joint fluid are commonly found in the knee joint with popliteal cysts. The pathologic essence of undifferentiated spondyloarthropathies is also tendonitis. When the inflammation invades the fingers and toes, it may be diffuse and swollen, resembling a waxing gynecomastia. (3) Lower back pain is also an early symptom of the disease, radiating to the buttock area and thighs, and is aggravated by bed rest and prolonged posturing. Chest pain is also common and is caused by inflammation of the tendons between the thoracic ribs and thoracic vertebral joints. In later stages, stiffness and pain in the back and neck and reduced mobility are present. 2. Extra-articular manifestations: Undifferentiated spondyloarthropathies may have various extra-articular manifestations that are associated with other spondyloarthropathies, such as fever, iritis, conjunctivitis, oral ulcers, urethritis, pulmonary fibrosis, atrioventricular block, pericarditis, aortic regurgitation and so on. When the above symptoms appear, it is necessary to go to the rheumatology and immunology department of the hospital in time for a clear diagnosis and early treatment to prevent further aggravation of the condition.