There is paucity of literature on liver histological spectrum of acute-on-chronic liver failure (ACLF). The aims of this study are to (a) to characterize the liver histological features in ACLF, (b) to correlate histological parameters with prognosis, and (c) to investigate whether etiology influences prognosis. We retrospectively studied liver biopsies of patients with ACLF. The histological findings were correlated with the clinical outcome. Fifty cases (median age, 39 years [10-69 years]; M/F, 3:1) were included. Etiology of acute insult was viral or alcohol in majority of the cases. Twenty-five patients survived (good outcome, 50%) and 25 died (poor outcome, 50%). On a univariate analysis, the outcome correlated with fibrosis, ballooning, eosinophilic degeneration, ductular proliferation, pericellular fibrosis, Mallory's hyaline, foci of confluent necrosis and/or bridging necrosis (CN/BN), cholestasis, apoptosis (present), and parenchyma left. However, on a multivariate analysis, only fibrosis, ballooning, ductular proliferation, apoptosis, and parenchyma left were found to be independently associated with outcome. Two distinct patterns of liver histology were observed: pattern I, observed in cases with poor outcome, showing marked ductular proliferation, coarse inspissated ductular bile plugs, eosinophilic degeneration of hepatocytes, foci of CN/BN, higher apoptosis, pericellular fibrosis, Mallory's hyaline, and higher stage of fibrosis. Pattern II is seen in cases with good outcome, show prominent hepatocyte ballooning with lesser parenchymal involvement by fibrosis and necrosis. Histological features of liver biopsy are: extent of fibrosis, ballooning, ductular proliferation, apoptosis, and lesser degree of parenchymal replacement by fibrosis or necrosis which correlates with the outcome in patients with ACLF. Two distinct patterns of liver histology are seen which help in prognostication.