Multiple sclerosis (MS) is an autoimmune multifactorial degenerative disease with detrimental affliction on central nervous system. MHC class I chain- related geneA,B(MICA and MICB) are nonclassical human leukocyte antigens that can affect on some diseases and also on transplantation. The purpose of this study was to evaluate the MICA and MICB MRNA expression in multiple sclerosis patients. In this study, we evaluated MICA and MICB MRNA expression in the peripheral blood mononuclear cells by reverse transcryptase-polymerase chain reaction(RT-PCR) in MS patients and normal controls. The results of this study showed that 32.6% of patients with progressive clinical outcome over expressed MICB genes in comparison with controls ( p=0.002). It is concluded that the high expression of MICB gene in MS patients is an important criterion of MS disease that it may be due to the interaction between MICB and its receptor on CD8+T or NK cells.