INTRODUCTION: Disasters can have deep physical and psychological impact among survivors. An extraordinary southwest monsoon has unleashed floods and landslides in Kerala state in 2018. Adolescents are more vulnerable to psychological impairment after a disaster and trauma during initial stages of life can etch an indelible signature in the individual's development and may lead to future disorders. OBJECTIVES: 1. To screen for PTSD and associated factors among adolescents 8 months post floods in selected schools in flood-affected areas of Alleppey district of Kerala 2. To compare the proportion of adolescents screened positive for PTSD in public and private schools. METHODOLOGY: A 3-month, Cross-sectional study was done among 670 adolescents in private and public schools using stratified sampling in Alleppey district. The study tool included a structured questionnaire that collected information on sociodemographics, flood-related variables, Trauma screening questionnaire and academic performance. RESULTS: The mean age of the participants was 16.03 ± 0.73 years with almost equal gender distribution. One-third of students reported flood-related damage to house/property, and a few lost their pets. Nearly 50% of the students reported that they still re-experience and get upsetting memories about flood events. The prevalence of probable PTSD noted to be 34.9%. We observed that 31% of students in public school screened positive for PTSD compared to 38.8% of private school students. (odds ratio = 1.409, CI 1.024-1.938). Male gender (Odds ratio = 1.503, CI 1.093-2.069), higher age (Odds ratio = 1.701, CI 1.120-2.585), damage during floods (Odds ratio = 2.566, CI 1.814-3.630), presence of morbidity (Odds ratio = 3.568, CI 1.888-6.743), camp stay (Odds ratio = 3.788, CI 2.364-6.067) and loss of pets (Odds ratio = 3.932, CI 2.019-7.657) were the factors significantly associated with PTSD. We noted a deterioration in academic performance in 45.9% of students who screened positive for PTSD. CONCLUSION AND RECOMMENDATIONS: High prevalence of stress disorder highlights the need for early identification and intervention for PTSD and including trained counsellors as a part of the disaster management team in future.