Continuous, reliable and real-time assessment of major determinants of cardiovascular function in preterm and term neonates has long been an elusive aim in neonatal medicine. Accordingly, aside from continuous assessment of heart rate, blood pressure and arterial oxygen saturation, bedside monitoring of major determinants of cardiovascular function of significant clinical relevance such as cardiac output, systemic vascular resistance, organ blood flow distribution and tissue oxygen delivery and coupling has only recently become available. Without obtaining reliable information on the changes in and interactions among these parameters in the neonatal patient population during postnatal transition and later in the neonatal period, development of effective and less harmful treatment approaches to cardiovascular compromise is not possible. This paper briefly reviews the recent advances in our understanding of developmental cardiovascular physiology and discusses the methods of bedside assessment of cardiovascular function in general and organ perfusion, tissue oxygen delivery and brain function in particular in preterm and term neonates. The importance of real-time data collection and the need for meticulous validation of the methods recently introduced in the assessment of neonatal cardiovascular function such as echocardiography, electrical impedance cardiometry, near infrared spectroscopy, visible light and laser-Doppler technology are emphasized. A clear understanding of the accuracy, feasibility, reliability and limitations of these methods through thorough validation will result in the most appropriate usage of these methods in clinical research and patient care.