Doppler measurements of blood flow velocity were obtained from the superior mesenteric artery (SMA), coeliac axis, and anterior cerebral artery (ACA) of 19 infants with suspected necrotising enterocolitis, which was classified as confirmed (n = 9) or unconfirmed (n = 8). Infants with confirmed disease were compared with controls who were either enterally fed or who were receiving intravenous fluids. SMA velocity was significantly higher in the infants with confirmed necrotising enterocolitis (36.5 cm/s) than in unfed controls (20.4 cm/s) or infants with unconfirmed enterocolitis (19.6 cm/s). Three infants with confirmed disease had data from before the onset of symptoms. One had low SMA velocity on the first day of life, and one showed no increase in SMA velocity after enteral feeds were started. SMA velocity is increased when infants develop symptoms of necrotising enterocolitis, suggesting that total gut ischaemia is not present at the time that the disease is clinically apparent, although it may precede the onset of symptoms and play a part in the pathogenesis of the disorder.