When echocardiography is necessary in the newborn period, it often is needed urgently. ( 1) However, staffing, organizational, and geographic limitations make it unlikely for pediatric cardiologists to provide 24-hour coverage for echocardiographic assessment of sick newborns in most centers. (2) Pediatric cardiology services also could be overwhelmed with requests for assessments of ductal shunting in preterm infants who have yet to develop clinical signs. (3) In many parts of the world, literature on the value of early hemodynamic assessment and increased access to ultrasonography equipment with improving image quality has motivated neonatologists to develop echocardiographic skills. As a result, echocardiography is increasingly considered an integral component of the assessment of the critically ill newborn. (2)(4)(5) An increasing number of neonatologists are undertaking assessments of functional hemodynamic status by echocardiography, with particular interest in volume of ductal shunt, (3) severity of persistent pulmonary hypertension, (6) and detection of low systemic blood flow. (7) In addition, some neonatologists have assumed the responsibility of excluding structural congenital heart disease in newborns presenting with cyanosis or a cardiac murmur. This review describes the principal applications of echocardiography by the neonatologist, with some practical guidance on method of assessment and interpretation of findings. Echocardiography is highly user-dependent. (8) The primary concern about neonatologists performing echocardiography has been the potential for misdiagnosis, particularly failure to recognize cardiac disease. There is scope for error in the diagnosis of both structural and functional cardiac pathology. Although errors in assessment of structural cardiac disease usually become evident over time, cardiac function changes dramatically during the neonatal period, so it is more difficult to assess whether interoperator discrepancies in functional assessment are due to observer error or true functional change. Some reports have suggested an unacceptably high error rate in the diagnosis of structural …