Abstract: The calf thymosin used, were extracted by dialysis methods. Its molecular weights were below 6000 Daltons.So this preparation was rather safe; it is not necessary to have a skin test before injection. About several thousands injections had been used no allergic reaction occurred.Particularly, in. using this preparation, the side reactions similar to those of corticosteroid hormones might be avoided. During 1978-1980, there were 44 cases (36 cases of SLE, 8 cases of DLE) of autoimmune disorders treated with the preparation. The results were encouraging. The clinical signs and symptomes were completely or nearly almost controlled is all patients. The.effective rates were 96.6%.LTT values rose to normal,in 15 of 19 cases. The LE phenomenon completely subsided in 26 cases. ANA tests turned to negative in 20 of 23 cases. This is only a preliminary result, further observations have to be done.