A case-control study was undertaken in Basrah Maternity and Children Hospital, Iraq. We studied 148 children who were admitted to hospital with severe pneumonia according to the World Health Organization (WHO) criteria and the controls were 250 children attending the out-patient department for non-severe respiratory infections. Significant risk factors were younger age (2-6 months), low parental education, smoking at home, prematurity, weaning from breast milk at < 6 months, a negative history of diphtheria, pertussis and tetanus vaccination, anaemia and malnutrition.