The pathogenic events that lead to amyotrophic lateral sclerosis (ALS) have not been elucidated. We previously described familial amyotrophic lateral sclerosis (FALS) caused by a Leu126delTT mutation in the Cu/Zn superoxide dismutase gene (SOD1) and have produced transgenic mice (TgM) carrying the same mutation (SOD1^L126delTT TgM), which exhibited distinct ALS-like motor symptoms and pathological findings. In this study, we analyzed gene expression in the spinal cord of SOD1^L126delTT TgM by cDNA microarray. Eleven genes were upregulated and two genes downregulated in pre-symptomatic TgM. In post-symptomatic TgM, 54 genes were upregulated and four genes downregulated. We performed real-time polymerase chain reaction (PCR) analysis of 10 of the 54 upregulated genes in the post-symptomatic TgM. The results of real-time PCR were consistent with those obtained by microarray for μ-crystallin (Crym), heat shock protein 1 (Hspb1/HSP27), serine proteinase inhibitor clade A member 3N (Serpina3n), complement component 1q subcomponent beta polypeptide (C1qb), cathepsin H (Ctsh) and polyadenylate binding protein-interacting protein 1 (Paip1). In immunohistochemical analysis, Hsbp1/HSP27 and Ctsh expression levels were increased in reactive astrocytes at the ventral horn of the spinal cord in post-symptomatic TgM, as were Crym, some of Ctsh and Paip1 in microglial cells. Increased expression of those genes was not observed in the control mice. These four genes may be related to the pathogenesis of FALS, especially with regard to the progression of reactive astrocytes and the inflammatory response of microglial cells.