Acute lower respiratory infection (ALRTI) is the leading cause of death in children below five years of age. Identification of modifiable risk factors of severe ALRTI may help in reducing the burden of disease.A hospital based case control study was undertaken to determine risk factors associated with severe lower respiratory tract infection (LRTI) in under-five children. A case definition of severe ALRTI as given by World Health Organization (WHO) was used for cases. Healthy children attending Pediatrics out patient department for immunization during study period were enrolled as controls. Details of potential risk factors in cases and controls were recorded in pre-designed proforma.512 children including 201 cases and 311 controls were enrolled in the study. On stepwise logistic regression analysis it was found that lack of breastfeeding (OR: 1.64; 95 percent CI: 1.23-2.17); upper respiratory infection in mother (OR: 6.53; 95 percent CI: 2.73-15.63); upper respiratory infection in siblings (OR: 24; 95 percent CI: 7.8-74.4); severe malnutrition (OR: 1.85; 95 percent CI: 1.14-3.0); cooking fuel other than liquid petroleum gas (OR: 2.5; 95 percent CI: 1.51-4.16); inappropriate immunization for age (OR: 2.85; 95 percent CI 1.59-5.0) and history of LRTI in the family (OR 5.15, 95 percent CI 3.0-8.8) were the significant contributors of ALRTI in children under five years. Sex of the child, age of the parents, education of the parents, number of children at home, anemia, inadequate caloric intake, type of housing were not documented to be significant risk factors of ALRTI.Lack of breast-feeding, upper respiratory infection in mother, upper respiratory infection in siblings, severe malnutrition, cooking fuel other than liquid petroleum gas, inappropriate immunization for age and history of LRTI in the family were the significant risk factors associated with ALRTI