To determine the prevalence of early childhood caries [ECC] and oral hygiene status of orphan children between the age group of 6 months to 6 years, a cross sectional study was conducted in thirteen different orphanages, located in four different areas of Chennai city, Tamilnadu. Diagnosis of dental caries was done based on National Institute of dental and craniofacial Research (NIDCR-1999) criteria and a modified version of the OHI-S (Greene and vermillion-1967) was used to record debris and calculus. The data was collected and analyzed using the SPSS package. A total number of 318 children participated in the study, out of which 155(48.7%) were males and 163(51.3%) were females. It was concluded that caries prevalence and severity are high in infants and preschoolers residing in orphanages.