Summary1. a technique using a radial‐carotid by‐pass is described, involving a rotary pump designed to have a variable, but predetermined, volume output.2. its use in 14 cases is described and it is suggested that it is most clearly indicated where advanced major cerebro‐vascular disease exists or where occlusion of the carotid has been shown to be deleterious.3. other methods of shunting are reviewed and some of their disadvantages out