Congenital hypothyroidism (CH) is the commonest preventable cause of mental retardation in human species. It is so important for clinician to know its etiology epidemiology, clinical manifestation and treatment strategies. Since it is one of the rare serious diseases that should not be diagnosed clinically because late clinical features corresponds to advanced mental retardation, the neonatal screening detection is the best and preferable way of early diagnosis of this congenital disease. Confirmatory laboratory and radiological diagnostic tests should be performed immediately after the positive neonatal screening test. In order to prevent mental defects and to maintain long term clinical as well as biochemical euthyroidism in affected children its diagnosis approach, medical treatment and follow-up should be well established knowledge to all pediatricians during the childhood period and later on to general practitioners when these individuals grow up as adults. Congenital hypothyroidism is a potentially serious disease that we need to emphasize on early detection, using proper diagnostic tools and early and planned therapeutic approach.