Sixteen patients with severe rheumatoid arthritis, marked inflammation of the synonvial membrane and high rheumatoid titer were cannulated by the thoracic duct for a period rangin between 82 up to 100 days. The patients being not under any medication during that time. Quantitative and qualitative analysis of the lymphocytes were performed, as well as responses to mitogens, rheumatoid factor, circulating antibodies and delayed hypersensitivity. By the 14th day nearly all the patients had a partial or almost complete remission of their disease. No complications were observed. These results will be discussed.