Background: An outbreak of jaundice at a residential school in Palakkad was reported to the district health authorities from a self-administrative unit of the district in the end of March 2019. Subsequently, an epidemiological investigation was carried out with the aim to ascertain the etiological agent, describe epidemiological features and recommend control measures. Material and Methods:Inspection of the school and hostel premises, kitchen, water source and sanitary assessment were done. The total line list of affected students and people was made. Cases and unaffected people living in houses nearby the school were interviewed using a structured questionnaire. Water samples, soil samples, serum and stool samples from new cases were collected and tested for Hepatitis A. Descriptive statistics was used to depict the results. Results: The outbreak affected 565 people including 529 students, 30 staff and 6 others. The symptoms reported by the cases were tiredness, vomiting, fever and jaundice. Based on the onset of symptoms, the epidemic curve drawn showed two peaks, suggesting secondary cases. The majority of the cases occurred among those studying in class VIII (11.7%). All water, serum and stool samples from patients tested positive indicating Hepatitis A infection. The attack rate of Hepatitis A among students of the school was calculated to be 22.09%. The soil samples and blood samples from food handlers tested negative for Hepatitis A. The distance of the well from the septic tank was measured to be 11.5m.Conclusion:The possibility of such a widespread contamination occurring could be the result of 2018 Kerala floods and/ or a major breakdown in the underground sewerage system leading to contamination of well waters with sewage. On the basis of this, various remedial measures like super-chlorination of wells, installation of better water purification system at the school, vaccination of students against Hepatitis A and widespread awareness regarding hepatitis A were suggested to be done.