Abstract: Thioredoxin (Trx) is a crucial protein for antioxidative defense, as well as a redox regulator of the intra- and extracellular signaling pathways and transcription factors. In this review, we focus on mammalian Trx and its association with Alzheimer’s disease (AD) and Parkinson’s disease (PD). Based on the evidence of neuroprotective effects of Trx, up-regulation of Trx may be a good strategy for prevention and treatment of AD and PD.