Seven cases with the syndrome of thalassemia minor and pauciarticular, non-erosive, seronegative arthritis are described. Other known causes of seronegative arthritis had been excluded. There was a predilection for middlesized joints such as ankles, wrists and elbows. Usually the synovitis was asymmetrical from onset, with one to eight joints affected. Finger or toe joint were usually spared. Extraarticular synovitis such as tenosynovitis or bursitis were not observed, nor were nodules, signs of vasculitis or visceral involvement. The course of this arthritis showed chronicity and mild, persistent, non-erosive synovitis without joint effusions. X-ray revealed juxtaarticular osteoporosis of the affected joints, characterized by a diminution of the number of trabeculae (hypertrophic atrophy) combined with broadening of the singular trabeculae; this picture is typical of hemoglobinopathies. - Computed tomography showed a probable slight deficit of bone mineralization. Laboratory investigations including ESR, routine immunological tests, blood chemistry, and HLA-tissue typing were all normal. - The combination of this peculiar arthropathy with thalassemia minor would appear to be worthy of note and requires a further search among the forms of arthritis of unknown origin.