A pre experimental one group pre test post test was conducted to assess the effectiveness of health education programme on knowledge and practice on home care management of diarrhoea among 50 mothers of underfive children in selected wards of Arattupuzha Panchayat. A structured questionnaire was used to assess the knowledge of the mothers and an observational checklist to assess the practice of ORS preparation. The study results found that majority of mothers had poor knowledge in the areas of signs and symptoms 26(52%) and preparation of ORS 22(44%). The mean post test knowledge score (26.1) is significantly higher than the mean pre test score (13.36), shows the effectiveness of the educational programme (p<0.05). Only 3(6%) had good practice on ORS preparation and the mean post test practice score (8.98) is significantly (p<0.05) higher than the pre test practice score (5.06). Thus the study findings strongly suggest that the health education programme is inevitable to improve the knowledge and practice of the mothers, thereby reducing the child mortality due to dehydration and prevent the occurrences in future.