A microcomputer-based technique is described for processing blood-velocity signals after they have been spectrally analysed. The system consists of a real-time dual channel spectrum analyser interfaced to a BBC model B microcomputer. The microcomputer is programmed to store and display in real-time spectral information received from the analyser. Stored sonograms can be readily retrieved from memory on request and displayed on the microcomputer's TV-monitor for viewing and/or subsequent numerate interogation. The proposed system is software controlled and is therefore both versatile and expandable, enabling accommodation of future sonagram processing methods and new diagnostic parameters.