Objectives: The aim of the study was to compare superior mesenteric artery (SMA) flow in premature infants with parenteral and enteral nutrition. Methods: A prospective study was conducted on 2 groups of preterm infants with gestational age of 280/7 to 366/7 weeks: group 1 did not qualify for early enteral feeds and received parenteral nutrition (PN), and group 2 received early enteral feeding. SMA peak systolic velocity (PSV), end diastolic velocity (EDV), and pulsatility index (PI) were measured using Doppler ultrasound before starting feeds at day 1 and at day 5. Results: The study recruited 40 infants; 20 in each group. At baseline, PSV, EDV, and PI did not differ between groups. At day 5, enteral nutrition was associated with significant increases in PSV (91.53 AE 29.15 vs 65.49 AE 19.18, P ¼ 0.003) and EDV (15.91 AE 7.01 vs 11.65 AE 5.58, P ¼ 0.026) and a decrease in PI (1.28 AE 0.40 vs 2.48 AE 0.83, P < 0.001). Regression analysis to control for confounders showed enterally fed infants to have increased PSV (adjusted odds ratio [aOR] ¼ 25.45; 95% confidence interval [CI]: 8.53-42.38, P ¼ 0.004) and EDV (aOR 8.630; 95% CI: 2.987-14.273, P ¼ 004) and decreased PI (aOR ¼ À1.133; 95% CI: À1.603 to À0.664, P < 0.001). Infants in the PN group later developed more frequent feeding intolerance when compared with the enterally fed group (65% vs 15%, respectively, P < 0.001). Conclusions: In preterm neonates, early EF is associated with increased SMA blood flow, decreased vascular intestinal resistance, and less frequent incidence of feeding intolerance.