Recent research has extended the role of the neurohormone oxytocin far beyond mating and bonding. Oxytocin now appears as a cornerstone that allows individuals to adapt their group interaction in a flexible, age and context-dependent manner. Accordingly, the central oxytocin system has been studied mainly in regions that belong to the "social brain", but not in the cerebellum - a structure traditionally not considered part of it. Recent data challenged this traditional view by showing that the cerebellum actually contributes to cognitive, emotional, and perceptual brain functions. In addition, the cerebellum - a major subcortical checkpoint connected to all regions of the cerebral cortex - contributes critically to brain development. On this base, we studied the oxytocin system in the cerebellum of the mouse.Using immunohistochemistry and fluorescent in situ hybridization (FISH), we detected oxytocin and its precursor in the cerebellar cortex and deep nuclei at all postnatal stages and in the adult. Oxytocin-positive fibers were present in the granular and Purkinje cell layers as well as in the deep-cerebellar-nuclei and white-matter. We detected oxytocin-receptors (OXTRs) in the cortex and in the deep-cerebellar-nuclei at all ages, the labeling being stronger in young than in adults. OXTRs were detectable in Purkinje cells, in scattered midsize neurons of the granular-layer (likely Golgi-cells), and in the deep-cerebellar-nuclei. We also performed FISH to detect OXTR mRNAs, at 11 PND and in the adults, males and females. FISH confirmed OXTR immunolabeling. We observed no gross differences between sexes, whatever the method and the age.