OBJECTIVES To assess the findings of colour-flow Doppler ultrasonography (DUS) in the diagnosis of vesico-ureteric reflux (VUR), as an alternative to the primary diagnostic tool, voiding cysto-urethrography (VCUG). PATIENTS AND METHODS Thirty-five children (aged 2-15 years) were examined for VUR by DUS and standard VCUG. All patients underwent DUS and VCUG within 48 h but the findings of the latter were not reported to the ultrasonographer. The DUS was undertaken using a colour Doppler real-time system; a positive ultrasonogram was defined by visualizing Doppler signals from the bladder to the ureter during the course of bladder filling. RESULTS Of the 70 ureters assessed, 28 were refluxing on DUS and 29 on VCUG; there were two false-positive and three false-negative results. Comparing the two methods showed DUS to be 90% sensitive with a specificity of 93% for detecting VUR. Four patients underwent reimplantation during their treatment. DUS findings correlated well with standard VCUG in these patient as a method of follow-up. CONCLUSION DUS can be used as an alternative to standard VCUG for screening and following VUR. In addition, DUS avoids the danger of exposure to ionizing radiation and the unpleasant catheterization that many of these children fear.