Iodine deficiency disorder (IDD) was first described by Hertzel in 1982, denoting all the affects of the deficiency on population growth and development. Iodine is an essential micro nutrient present in thyroid hormone, thyroxine T4 and tri iodo thyroxine T3, essential for normal mental and physical development in humans. Goiter and cretinism are the two forms which are commonly seen as a result iodine deficiency. Manifestations of the deficiency in a population can be in the form of lethargy which eventually can lead to irreparable losses in terms of fall in work output in households and work place. Cretinism is described in severe deficiency of iodine during intra uterine life leading to disorders like mental retardation, deaf mutism and spastic paralysis of legs in varying degrees. IDD may be mild, moderate or severe depending upon the urinary iodine level and prevalence of goiter. Geoclimatic conditions and drugs have been implicated as anti thyroid factors which can contribute to this deficiency. Prevention of IDD involves prophylaxis by fortification of food items like salt which is now routinely done at the national level.