Quiescin-like sulfhydryl oxidases (QSOX) represent a new emerging family of enzymes which catalyse the oxidation of sulfhydryl groups to disulfides in peptides and proteins. Orthologous and paralogous members have been found in a wide range of multicellular organisms. They have been linked to fundamental molecular and cellular mechanisms such as protein folding, regulation of the redox state, control of the cell cycle and apoptosis signalling. In rat, the QSOX protein (rQSOX) was initially isolated and sequenced from seminal vesicles. In the present review, we report the current knowledge of rQSOX in the adult and developing central nervous system and highlight its importance in this model. Its occurrence in peripheral organs will also be briefly evoked. The gene is differentially expressed in peripheral organs and in the central nervous system in which two transcripts arising from alternative splicing were identified. The proteins encoded by these transcripts only differ by the occurrence of an additional sequence at the carboxy-terminal end of the long isoform. In peripheral organs, the enzyme is mainly localized in cells specialized in secretion, suggesting it could intervene in the oxidative folding of secreted proteins and hormones. In brain, rQSOX is widely distributed throughout the rostro- caudal extent, specifically in neuron synthesizing disulfide-bonded neuropeptides. Its ultrastructural localization indicates that it can be secreted and play a role in the extracellular matrix. The ontogenesis of rQSOX expression is closely related to the maturation of some neuronal systems, suggesting that the enzyme could be involved in migration, settlement and maturation of neurons.