Several methods for evaluating left ventricular stroke volume (SV) in neonates using echocardiography have been reported. However, no studies on methodologic comparison of SV with three-dimensional (3D) echocardiography are available. This is the first detailed report on a methodologic comparison of SV in the early neonatal period. The study group included 70 normal neonates (35 boys and 35 girls). An iE33 echocardiograph and Q-LAB supplied by Philips Electronics were used to examine and calculate volumes. Comparisons of SV were performed using Teichholz (T), the velocity time integral (VTI), Pombo (P), modified Simpson (MS), and 3D methods with normal neonates who had no persistent ductus arteriosus less than 7 days after birth. The mean SVs were 33.7 mL/m(2) (T), 30.6 mL/m(2) (VTI), 22.0 mL/m(2) (P), 17.5 mL/m(2) (3D), and 14.9 mL/m(2) (MS) using Haycock's formula of body surface area. The stroke volumes differed significantly depending on the different methods. The correlation coefficient was highest between the MS and 3D methods. The SVs of the T and VTI methods were significantly greater than those previously reported, and it seemed inappropriate to evaluate volumes in neonates. The 3D and MS methods were appropriate for measuring SV in neonates during the early neonatal period.