Detail observations of clinical course and prognosis were carried out in 54 cases with wide involved ulcerative colitis which could followed by medical management. Our medical therapy against patients with active but uncomplicated ulcerative colitis is based upon immunological and hematological findings. Several authors reported generally a poor lym-phocyte response in ulcerative colitis, but we found invariable high PHA responses in several cases of initial active stage in untreated ulcerative colitis, and then in remission there were always low values. Influence of salicylazosulphapyridine (SASP) on peripheral blood lym-phocytes in healthy subjects was examined by chromium release assay. Inhibition by SASP on the PHA-induced cytotoxic action of human lymphocytes was observed by using mouse L cells as target cell. This results suggest that SASP has some inhibitory action for immune system. It was emphasized that SASP is the drug of first choice in patients not only with mild and moderate colitis but also with severe colitis.The clinical course should be followed by checking the appearance and laboratory findings such as WBC counts, body temperature and ESR. In addition, the findings of the blood coagulation and fibrinolysis are necessary to detection of prognosis.The only SASP administration recovered complete remission in 57 % of entire colitis and in 85% of left side colitis. Patients who felt epigastral discomfort or had leucopenia could be exchanged one part of oral administration of SASP to suppositorie.