Introduction Overweight in childhood is an emerging health problem in developing countries. Objective To determine the prevalence of overweight and obesity among grade five school children in schools of Gampaha Medical Officer of Health(MOH) area. Methods A descriptive cross sectional study was carried out among the grade five students in government and private schools in Gampaha MOH area during September and October 2007. Nine schools from a total of 46 were selected applying multistage stratified cluster sampling method. Overweight and obesity were detected using age and sex specific body mass index cut-off points recommended by International Obesity Task Force. Results Among the 1110 children included in the study, the prevalence of overweight was 11.3 % (95%CI: 9.4-13.2). The prevalence of obesity was 2.2% (95% CI: 1.3-3.0). The overall prevalence of overweight and obesity were 13.4% and 13.6% for female and male respectively. Prevalence of overweight in private schools was higher than in government schools (p Conclusion Prevalence of overweight and obesity in grade five students in schools of Gampaha MOH area were 11.3 % and 2.2%. Prevalence was higher in private schools. DOI: http://dx.doi.org/10.4038/jccpsl.v19i2.7576 Journal of the College of Community Physicians of Sri Lanka 2014 June 19(2): 11-16