Aim of the study: The objective of this study is to measure the level of potent profibrotic cytokine transforming growth factor beta1 (TGF-β1) in cases of respiratory distress syndrome, evaluating its role as a predictive marker for the development of chronic lung disease of prematurity (CLD). Methods: This study was carried out on forty five (45) preterm newborns selected from those admitted to neonatal intensive care unit (NICU) at Benha university hospital and Benha children hospital during the period from July 2010 to October 2011. Their gestational age ranged between 28-35 weeks. Inclusion criteria: gestational age of newborn more than 28weeks, Infant with respiratory distress syndrome and respiratory distress with subsequent need for artificial ventilation. Exclusion criteria: Infants with congenital anomalies. All patients were subjected to the following: Full history taking: including antenatal, natal and maternal history, gestational age by using Biallard score, body measurement; weight, length and head circumference, through clinical examination. And measurement of TGF-β1 in serum of selected newborns on (admission, 5-7days later and on 28th day after admission).Data was collected, revised and entered using the statistical package SPSS.