Background: Obesity amongst the children is increasing worldwide at an alarming rate in both developed and developing countries. Obese children are at higher risk of developing coronary heart disease, noninsulin dependent diabetes, respiratory disease etc. Methods: A case-control study, preceded by a cross sectional survey was conducted, aimed to estimate the prevalence rate and to identify the factors associated with the development of childhood obesity in Dhaka city. A multi stage probability proportionate to size (PPS) cluster sampling method was used to obtain the sample. To identify the obese children, a pre-tested questionnaire was used to collect data on age, weight and height among the randomly selected 5000 children of 2-10 years age group from 12 government primary and 23 private elementary schools, 4 hospitals, 8 health centres and 12 immunisation centres (on National Immunisation Days) from all the 12 thanas (civil administrative sub-districts) of Dhaka city. Survey included a medical history and physical examination to assess the eligibility of the subjects for the study.