A combined pulsed Doppler and linear array scanner is used to measure volume blood flow in 75 aortas and 45 umbilical veins of foetuses in the 3rd trimester. The mean aortic flow was 277 ml/min/kg and the mean umbilical venous flow was 122 ml/min/kg. Mean flow in the portal veins of normal subjects was found to be between 0.6 and 2.0 1/min. Clear signals were obtained from the adult kidney but no volume flow calculation has yet been attempted. The use of a spectrum analyser is considered fundamental to the accurate interpretation and processing of the Doppler signals. Medical and electronic artefacts are described which would not be detected without the use of an analyser. © 1985.