Amyotrophic lateral sclerosis (ALS) is a progressive, lethal, neurodegenerative disorder. The causes of ALS are still obscure. Accumulating evidence supports the hypothesis that oxidative stress and mitochondrial dysfunction can be implicated in ALS pathogenesis. DJ-1 plays an important role in the oxidative stress response. The aim of this study was to discover whether there are changes in DJ-1 expression or in DJ-1-oxidized isoforms in an animal model of ALS. We used mutant SOD1(G93A) transgenic mice, a commonly used animal model for ALS. Upregulation of DJ-1 mRNA and protein levels were identified in the brains and spinal cords of SOD1(G93A) transgenic mice as compared to wild-type controls, evident from an early disease stage. Furthermore, an increase in DJ-1 acidic isoforms was detected, implying that there are more oxidized forms of DJ-1 in the CNS of SOD1(G93A) mice. This is the first report of possible involvement of DJ-1 in ALS. Since DJ-1 has a protective role against oxidative stress, it may suggest a possible therapeutic target in ALS.