The current study was done to evaluate physical growth and mental development of children with congenital hypothyroidism (CHT) attending Pediatric Endocrine OPD BIRDEM, Dhaka, Bangladesh. It is a cross sectional study done in a period of 1 year (May 2008 to April 2009)among total number of 80 children with CHT.History and thorough physical examination was carried out including anthropometric measurement, and developmental assessment done according to Denver developmental screening test. Congenital Hypothyroidism (CHT) is a serious condition of newborn babies, which leads to permanent mental and physical retardation if not identified within first few weeks of life. There is an inverse relationship between age at diagnosis, commencement of treatment and neurodevelopmental outcome. In the present study, comparison between early and late treated group revealed that, children who were diagnosed at early age and started treatment early had favorable outcome in terms of growth and development in comparison to children with CHT who had delay in diagnosis and commencement of treatment.