ABSTRACT
About 60% of fullterm and 80% preterm of infants develop neonatal jaundice which is either physiological or pathological in nature. One of modality of treatment is phototherapy which was discovered by the observation of one of the nurses when she noticed the decline in severity of jaundice in newborn infants who exposed to sun light. There are different colors of light that used in phototherapy, the best one is blue, then yellow then white, the action of phototherapy is made absorption of light by skin and by two mechanism photoisomerization and conversion into non toxic substance called lumirubin. The photothearpy used light with wave length 420-470 nm, so there is common mistake in population when they use the ordinary light at home as photothearpy this may expose the infant to danger of light and to delay in management of jaundice