Abstract Background Elevation of the head of bed (HOB) increases intra-abdominal pressure (IAP), but the effect of body position on abdominal splanchnic perfusion is not clear. The current study aimed to evaluate the effect of body position on the superior mesenteric artery (SMA) and the celiac artery (CA) blood flow by Doppler ultrasound in mechanically ventilated patients with intra-abdominal hypertension (IAH). Methods This prospective cohort study included 53 mechanically ventilated patients with IAH. IAP, hemodynamic variables, and Doppler parameters of the SMA and CA were measured in the supine position. The measurements were repeated after the HOB angle was raised to 15° for 5 min and similarly at HOB angles of 30° and 45°. Finally, the patient was returned to the supine and these variables were re-measured. Results The median (interquartile range, IQR) superior mesenteric artery blood flow (SMABF) decreased from 269 (244–322) to 204 (183–234) mL/min and the median (IQR) celiac artery blood flow (CABF) from 424 (368–483) to 376 (332–472) mL/min (both p