Introduction: Jaundice affects nearly 60% of term and 80% of pretermneonates during the first week of life. Unconjugated hyperbilirubinemia mayresult in severe medical conditions when left untreated. The most serious ofthem is encephalopathy. Cardiac affection was also reported in many studies.The aim of this work: was to study prospectively the effects of unconjugatedhyperbilirubinemia on the cardiovascular status and myocardial function injaundiced neonates admitted to Cairo University NICU over a period of 3consecutive months (May to July 2009).Patients and methods: The study included 135 neonates. We studied theimpact of different clinical parameters (e.g. mode of delivery, gestational age,admission weight, etc.) and laboratory parameters (e.g. level of total andunconjugated bilirubin on admission and after 48 hours, hemoglobin, etc. ) onthe cardiac functions measured by echocardiography.Results: The studied patients represented 46.1% of all admissions in these 3months. Males were more prevalent than females (54.8% versus 45.2%). Thegestational ages ranged from 35 weeks to 40 weeks, and their admission’sweights varied from 1.5 to 4.5 kg. The jaundice was noticed from day 1 to aslate as day 7, while the admission ages ranged from 1 day to 27 days. Onadmission, total serum bilirubin ranged from 6.7 to 45.8 mg/dl andunconjugated bilirubin ranges were from 6.4 to 42.9 mg/dl. Other parametersalso were measured e.g. hemoglobin, albumin, B/A ratio, potassium etc.Nineteen percent of the studied cases had fractional shortening below 30% asdocumented by echocardiography, indicating affection of left ventricularsystolic function. Cases with cardiac affection had significantly higherbilirubin levels and B/A ratio on admission than cases without cardiacaffection. They also showed increased left ventricular enddiastolic, left ventricular endsystolic, aortic outlet and left atrial measurements. On followup after 1 month for reevaluation of their echocardiographic findings, only 10cases came. Three out of the ten cases had still an affection of cardiaccontractility and were referred to cardiology clinic.Conclusion: Neonatal unconjugated hyperbilirubinemia is still a main causeof admission to the NICU. The public and professional awareness of theproblems associated with neonatal jaundice should be highlighted andaffection of cardiac contractility should also be considered. Patients withsevere hyperbilirubinemia (> 25 mg/dl) are more susceptible to cardiacaffection. Early detection and follow up of cases with high unconjugatedhyperbilirubinemia are recommended