Objective: To describe the prevalence and factors associated with undernutrition in children aged 6-59 months in a rural area of Sri Lanka. Method:A community-based, cross-sectional study was carried out among children aged 6-59 months attending well baby clinics in Dehiattakandiya Medical Officer of Health area from November 2016 to January 2017. Data collection was done using an interviewer-administered questionnaire. Weight and height measurements were taken with calibrated instruments. Data analysis was done using logistic regression by SPSS 16.0.Results: Four hundred and sixty four children were recruited having a mean age of 29.3 ±14.6 months; 53% were females. Prevalence of stunting, underweight and wasting was 36.4%, 42.9% and 19.0% respectively. The following independent associations were identified: for stunting-low birth weight, breastfeeding beyond 2 years, lower maternal education and paternal smoking; for underweight-birth order more than 2, low birth weight, breastfeeding beyond 2 years, lower maternal education and paternal smoking and alcohol use; for wasting-male sex, low birth weight and paternal smoking. _________________________________________