Liver regeneration is a clinically significant tissue repair process, which is suppressed by chronic alcohol intake through poorly understood mechanisms. Recently, miR-21 has been suggested to serve as a crucial microRNA regulator driving hepatocyte proliferation after partial hepatectomy (PHx) in mice. However, we reported recently that miR-21 is significantly upregulated in ethanol-fed rats at 24h after PHx despite inhibition of cell proliferation, suggesting a more complex role for this microRNA. Here, we investigate how inhibition of miR-21 in vivo affects the early phase of liver regeneration in ethanol-fed rats. Chronically ethanol-fed rats and pair-fed control animals were treated with AM21, a mixed locked-nucleic acid/DNA analogue antisense to miR-21 that inhibited miR-21 in vivo to undetectable levels. Liver regeneration after PHx was followed by cell proliferation markers, gene expression and microRNA profiling, and cell signaling pathway analysis. Although liver regeneration was not significantly impaired by AM21 in chow-fed rats, AM21 treatment in ethanol-fed animals completely restored regeneration and enhanced PHx-induced hepatocyte proliferation to levels comparable to untreated or chow-fed animals. In addition, a marked deposition of α-smooth muscle actin, a marker of stellate cell activation, which was evident in ethanol-treated animals after PHx, was effectively suppressed by AM21 treatment. Gene expression analysis further indicated that suppression of stellate cell-specific pro-fibrogenic profiles and NOTCH signaling contributed to AM21-mediated rescue from deficient hepatocyte proliferation in ethanol-fed animals. Our results indicate that the impact of miR-21 balances pro-proliferative effects with anti-proliferative pro-fibrogenic actions in regulating distinctive regenerative responses in normal versus disease conditions.