A 70% partial hepatectomy (70%PHx) induces cell proliferation until the original mass of the liver is restored. Mitochondria are involved directly in the process of liver regeneration (LR); however, their role in the early phase of LR is not clear. In an attempt to identify mitochondrial proteins that are correlated with the early phase of LR, we obtained a mitochondrial fraction via Nycodenz® density gradient centrifugation and subcellular proteomic analysis was performed. The mitochondrial proteins were separated by two-dimensional gel electrophoresis and identified by mass spectrometry. Compared to the sham-operation control group, 3 proteins were up-regulated and 22 proteins were down-regulated at 24 h after 70%PHx. We identified 22 differentially expressed proteins that were associated with carbohydrate metabolism, lipid metabolism, the respiratory chain and oxidation–phosphorylation, biotransformation and other metabolic pathways. Prohibitin, a proliferation-regulating protein that was down-regulated at 24 h after PHx, was analyzed by applying RNAi (PHBi) with BRL-3A. This demonstrated a decreased mitochondrial membrane potential, implying a potential role in maintaining mitochondrial integrity. These results indicated that hepatic mitochondrial adaptations to LR after 70%PHx affect various cellular metabolic pathways, which advances our knowledge of the role of mitochondria in the early phase of LR. J. Cell. Biochem. 105: 176–184, 2008. © 2008 Wiley-Liss, Inc.