INTRODUCTION AND OBJECTIVES: To describe the socio-economic inequalities in selected health related risk factors among slum dwellers in Colombo Municipal Council area (CMC). METHODS: This descriptive cross sectional study included 1000 slum dwelling households (HH) selected using multistage random sampling from twenty five neighborhoods in CMC during 2009. Data were collected by data collectors using a predesigned questionnaire and analysed using SPSS software. When appropriate, comparisons were made with the findings of Census of Population and Housing, 2001. Socio-economic quintiles were obtained from a composite score comprised of 13 variables. RESULTS: There were 5375 HH members in 1000 HH. Proportion of houses with five to nine HH members was higher in slums (60.7%, n = 607) than in CMC (45.2%, n = 51812, in 2001 census). Almost one fourth (24.9%, n= 774) of those aged ^8 had only primary or no formal education. Some health risks among the participants included usage of kerosene oil (55.5%, n - 2981) and firewood (16.1%, n= 863) for cooking, no separate kitchen inside the house (45%, n =2418), metal roof (21%, n=1131) and wooden wall (13.6%, n=730). Of the males aged >18 years, 42.6% (n=1491) reported consuming alcohol and 34.9% (n=509) reported smoking. Health related risk factors (n=12) showed significant gradients along the socio-economic quintiles. CONCLUSIONS: Several health risk factors were observed in higher proportion among slum dwellers than the overall population in CMC. Significant gradient of inequalities in health related risk factors were observed among socio-economic quintiles of slum dwellers in CMC