Background: Acute-on-chronic liver failure (ACLF) is a distinct clinical entity in the spectrum of chronic liver disease with a rapid downhill course and associated with poor outcome. The Asian Pacific Association for the Study of the Liver (APASL) consensus defined ACLF as “an acute hepatic insult manifesting as jaundice (serum bilirubin ≥ 5 mg/dL) and coagulopathy (INR ≥1.5) complicated within 4 weeks by ascites and/or encephalopathy in a patient with previously diagnosed or undiagnosed chronic liver disease”. Data regarding ACLF are scarce, heterogeneous, and mostly retrospective specially in the Asian subcontinent. In accordance with these observations, this study was conducted to review clinical profile, primary etiologies, precipitating insults, laboratory parameters, outcome and predictor of mortality in patients with ACLF in a tertiary care hospital of North India. Aim: To study the Clinical profile of patients with acute-on-chronic liver failure (ACLF) and its prognostication Methods: In this prospective study, 178 consecutive patients of ACLF as per APASL definition were included. Etiology of cirrhosis, precipitating events, frequency of organ failure and predictor of mortality were assessed. Results:A total of 178 patients were included with mean age 44 (range 18-42) years and139 were male (78%).Jaundice, followed by ascites with or without hepatic encephalopathy, was the most common presentation (162/178, 91%). Among patients who had esophageal varices (67.24%), approximately half (46%) had large esophageal varices. Hyponatremia was noted in 39% patients of ACLF. The most common causes of cirrhosis were alcohol (47%), cryptogenic (27%) followed by HBV (18%) and HCV infection (7%). Most common precipitating events were infection (47.6%) followed by active alcoholism (27.6%).Most of the patients had single precipitant (88.7%).Out of 114 patients of CLD because of alcohol and HBV (64% of total patients), ACLF was caused by reactivation of underlying disease itself in 65 patients (36.5%). 86.5% patients had organ failure, as per EASL CLIF-SOFA consortium. Among patients who qualified as ACLF by EASL-CLIF criteria, only a small percentage (≈17 %) are qualified as ACLF grade 1 whereas 56% had ACLF of grades 2 and 3 and associated with significantly higher mortality (56%). The presence of no organ failure, single organ failure and two organ failure carried a mortality rate 29.16%, 36.50% and 42.10% respectively. Whereas, more than 70% patients die within 28 days if had ≥ 3 organ failure. Overall 28-day and 3-months mortality was 43.82 % and 58.43%. Non survivors (n=78) had a significantly higher CTP score (p value=0.04), MELD score (p value=0.002), CLIF-SOFA score (p value=0.007), and ≥3 organ failure (p value=0.02) as compared to survivors (n=100). Conclusion: Infections as acute precipitating events of ACLF are much more common in this region as compared to the west. ACLF patients have a high prevalence of organ failure and severity of organ failure as well as baseline severity of liver disease determines the high mortality.