Chronic lung disease is a common and important form of neonatal mortality and morbidity which may be associated with an adverse long term pulmonary and neuro developmental outcome. Improvement in the survival of premature infants has led to an increased number of infants with this disorder. This increase, places a heavy burden on health care resources, as these infants, frequently need re admission to hospital following discharge, especially so in the first two years after birth and, even in adolescence, lung function abnormalities and persistent respiratory symptoms have been recognized or identified.