Pathways of liver fibrosis are controlled by connective tissue growth factor (CCN2). In this study, CCN2 was identified as a target of miR-199a-5p, which was principally expressed in quiescent mouse hepatic stellate cells (HSCs) and directly suppressed production of CCN2. Up-regulated CCN2 expression in fibrotic mouse livers or in activated primary mouse HSCs was associated with miR-199a-5p downregulation. MiR-199a-5p in quiescent mouse HSCs inhibited the activity of a wild-type CCN2 3 0 untranslated region (3 0 -UTR) but not of a mutant CCN2 3 0 -UTR lacking the miR-199a-5p-binding site. In activated mouse HSCs, CCN2, a-smooth muscle actin, and collagen 1(a1) were suppressed by a miR199a-5p mimic, whereas in quiescent mouse HSCs, the inhibited CCN2 3 0 -UTR activity was blocked by a miR-199a-5p antagomir. CCN2 3 0 -UTR activity in human HSCs was reduced by a miR-199a-5p mimic. MiR-199a-5p was present at higher levels in exosomes from quiescent versus activated HSCs. MiR-199a-5pecontaining exosomes were shuttled from quiescent mouse HSCs to activated mouse HSCs in which CCN2 3 0 -UTR activity was then suppressed. Exosomes from quiescent HSCs caused miR-199a-5pe dependent inhibition of CCN2, a-smooth muscle actin, or collagen 1(a1) in activated HSCs in vitro and bound to activated HSCs in vivo. Thus, CCN2 suppression by miR-199a-5p accounts, in part, for lowlevel fibrogenic gene expression in quiescent HSCs and causes dampened gene expression in activated HSCs after horizontal transfer of miR-199a-5p in exosomes from quiescent HSCs. (Am J Pathol 2016, 186: 2921e2933; http://dx