Context: Acetaminophen is an easily available and frequently abused over-the-counter drug both in the western world and India. It is one of the commonest cause of medication-related poisoning in the world. The spectrum of hepatotoxicity associated with Acetaminophen can extend froma mild liver disease to fulminant hepatic failure requiring transplant. The toxic component N-Acetyl-p benzoquinone imine (NAPQI) causes centrilobular hepatic necrosis. This study aims to find the predictor of duration of hospital stay in acute acetaminophen overdose. Aim: The study aims to find correlation between the amount of ingested Acetaminophen and initial International Normalized Ratio (INR) and the latter with duration of hospital stay among patients visiting the Emergency Medicine department (ED) with a single deliberate ingestion of Acetaminophen. Materials and Methods: Settings and Design: This is a retrospective, observational study done among patients presenting to the emergency medicine department in a tertiary care centre in South India with acute single deliberate ingestion of Acetaminophen. Study population belonged to 15-45 years age group. The period of study was during the years 2016-2019. Subjects and Methods: Baseline demographics and clinical characteristics were noted. Correlation between ingested Acetaminophen and initial INR within 24 hours of ingestion and between initial INR and duration of hospital stay was analyzed with scatter plot. Statistical Analysis used: Statistical analysis was done using IBM SPSS version 23.0 (SPSS Inc., Chicago, USA). The categorical variables are represented as percentages and continuous variables are represented as mean ± standard deviation (SD). To test the statistical significance of association of categorical variables, Pearson correlation coefficient (r) was used. A p-value of <0.05 was considered as statistically significant. Results: The present study included 52 patients who deliberately ingested acetaminophen, with 13 males (25%) and 39 females (75%) and mean age of 23.67 ± 6.9 years. History of previous psychiatric illness was noted in 23.1% patients. Gastric lavage and activated charcoal was done in 36 (69.2%) and 13 (25%) patients respectively. Ingested amount of Acetaminophen had statistically significant correlation with initial INR with a p-value of 0.004. It was also noticed that the initial INR value and duration of hospital stay had a statistically significant correlation with P-value of <0.001. Conclusion: The study concludes that there is correlationbetween the dose of Acetaminophen ingested and INR. INR value also had positive correlation with duration of hospital stay.