Three patients with an evident multiple sclerosis (MS) were observed in a dynamics of long-term immune therapy based on administration of rIFN-alpha preparation. Production of IFN-alpha and IFN-gamma by induced peripheral blood leukocytes (PBL) of the patients was tested simultaneously with detection of a response of PBL to in vitro IFN-alpha and IFN-beta priming action every 10th day of observation. It has been shown that positive clinical effect of rIFN-alpha therapy was associated with a partial restoration of initially decreased IFN-alpha and IFN-gamma production by PBL, and paralleled by increasing the cell IFN-alpha sensitivity. On the other hand, decrease of PBL response to in vitro IFN-beta action was related to augmentation of IFN-alpha and IFN-gamma production in the secondary progressive MS. The effect of rIFN-alpha administration on blood cell sensitivity to in vitro IFN-beta treatment was manifested by augmentation of PBL response in patient with the remitting MS. The data obtained allowed to suggest a possibility to combine a usage of rIFN-beta and rIFN-alpha in pathogenetical therapy of the remitting MS.