The liver is one of the most complex organs in the body, containing at least seven different cell types and carrying out over 5000 functions. The liver transplantation became a known and effective method for treating its end-stage insufficiency. In response to hepatocellular damage (viral, chemical or surgical injury) the liver mounts inflammatory, regenerative and repair processes with the aim of restoring the functional liver tissue mass. Restoration or liver regeneration after a partial hepatectomy has been scientifically observed since the late nineteenth century. By definition, liver regeneration is an orchestrated response induced by specific external stimuli, involving sequential changes in gene expression, growth factor production, and morphologic structure. During this process, the liver undergoes compensatory hyperplasia in order to reestablish the optimal mass set in relationship to its body size. Many growth factors and cytokines, most notably HGF, EGF, TGF-alpha, IL-6, TNF-alpha, insulin and norepinephrine, seem to play important roles in this process.