Introduction: In patients of Chronic Liver Disease (CLD), two types of acute decompensation can be seen, Acute on Chronic Liver Failure (ACLF) and Non Acute on Chronic Liver Failure (NACLF). There is difference in presenting symptoms, clinical signs, Ultrasonography (USG) findings and aetiological factors. Complications arising and its severity relayed to mortality also vary between two. Aim: To assess the difference and define the two types of acute decompensation. Materials and Methods: This was an observational, descriptive, longitudinal study based on prevalence of ACLF. All subjects meeting the eligibility criteria (acute decompensation was defined as set of jaundice or rise in S. Bilirubin levels >2 mg/dL, encephalopathy, development or increase in ascites, UGI bleed, increase in PT/INR by >1 second or S. Creatinine >0.5 mg/dL) were included in the study. These patients underwent estimation of haemogram, liver function tests, renal function tests, serum electrolytes (Na/K), viral serology (HIV/HBsAg/Anti-HCV/IgM HAV/IgM HEV), urine routine/microscopic examination and culture, stool routine/microscopic examination and culture (in cases of diarrhoea), blood culture, ascitic fluid analysis (if present) including culture/sensitivity, chest X-ray and USG abdomen. Data obtained were analysed qualitatively by Chi-square test and quantitatively by t-test. Results: In this study of 86 patients suffering from CLD, 71 (82.6%) were males and 49 (57%) patients were above 50 years of age. It was found that abdominal distension was the most common presenting symptom seen in 50 (58.1%) patients and the most evident clinical sign was icterus in 70 (81.4%) patients. The most common deranged laboratory parameter was elevated AST in 61 (70.9%) and anaemia in 51 (59.5%) patients. The most common USG finding was splenomegaly seen in 32 (37.2%) patients. Alcohol turned up to be the most common aetiological factor in 45 (52.3%) patients and HBV in 11 (12.8%) patients. The most common complication seen after three months of follow-up was variceal bleed in 33 (38.4%) patients and encephalopathy in 28 (32.6%) patients. The three months mortality in ACLF patients was 36.36% with overall Odds Ratio of 8.57. The common complications of acute decompensation in 22 cases of ACLF were multi-organ failure. Conclusion: ACLF as an entity in acute decompensated CLD patients was more common in patients who presented with altered sensorium, jaundice and decreased urine output. On three months of follow-up, Renal failure was most significant complication followed by hepatic encephalopathy and respiratory infections. The overall mortality in ACLF increases with complications.