The paper provides the results of intracardiac circulation ultrasound study in 37 preterm neonatal infants, including 24 patients with severe respiratory distress syndrome (RDS), receiving the exogenous surfactant Curosurf in the complex therapy of the disease. A control comprised 12 apparently healthy preterm neonates who had no clinical signs of RDS in the early adaptive period or artificial ventilation (AV). Both groups were similar in the major anthropometric characteristics and gestational age. The objective of this investigation was to make Doppler echocardiographic study of blood flow through all cardiac valves in the newborn with RDS during AV. The investigation indicated that the neonates with severe RDS had increases in peak blood flow velocity and in peak pressure gradient through the valves of the great vessels: the aorta and pulmonary trunk, and abnormal regurgitation flow mainly through the pulmonary arterial valve, which was a sign of intensive hemodynamic adaptation in the acute phase of disease. By the third day of life, some neonatal infants without clinical signs of RDS were observed to have signs of intensive hemodynamic adaptation: increases in peak blood flow velocity and in peak pressure gradient through the valves of the pulmonary trunk. Irrespective of the specific features of the course of an early neonatal period, neonatal infants need Doppler echocardiographic monitoring for the evaluation of intracardiac hemodynamics.