Background: Total serum bilirubin (TSB) testing is typically necessary for the management of jaundiced neonates; in infants not undergoing phototherapy, transcutaneous bilirubin (TCB) was more accurate. It is preferable to evaluate TCB at the forehead during phototherapy as opposed to the sternum. Objectives: This study aimed to confirm the accuracy of TCB in the neonatal intensive care under phototherapy and compare forehead and sternum as the TCB assessment site. Patients and methods: A Prospective observational study was conducted on 88 Neonates under phototherapy conducted at the NICU of Menoufia University Hospital and AL Helal Insurance Hospital, during the period from august 2022 to September 2023. Results: ROC curve analysis showed that cutoff point of TSB in neonates with hyperbilirubinemia was 9.85 mg/dl, with sensitivity of 87.7%, specificity of 27.3% at AUC of 0.743, cutoff point of TCB forehead for detection of jaundice in neonates with hyperbilirubinemia was 7.350 mg/dl, with sensitivity of 84.6%, specificity of 90.9% at AUC of 0.628 and cutoff point of TCB sternum for detection of jaundice in neonates with hyperbilirubinemia was 3.70mg/dl, with sensitivity of 74.3%, specificity of 81.8% at AUC of 0.608 Conclusion: The variations in skin composition that have been noticed in the TCB measurements at the forehead and sternum may be the cause of the variances in TCB estimate. This is because the concentration of collagen and melanin can alter the wavelength that TCB photometry detects.