In 61 patients with vesicoureteral reflux renal scar formation was diagnosed by excretory urography and 123iodine-hippurate scintigrams. Scar formation on the nephrograms was detected in the upper, middle and lower zones of the kidneys on tomography exposures. Scintigraphic detection of scars was performed on the computerized uptake of the parenchymal phase. Maximal time elapse between the 2 investigations was 1 year. Excretory urography revealed 37 kidneys with a total of 74 regional scars. On scintigraphy 57 kidneys were judged to have 102 scars. There were 281 regions judged to be identical on the scintigram and the nephrogram. A true positive ratio (sensitivity) of 0.46 and a true negative ratio (specificity) of 0.90 were noted for the excretory urogram, compared to a sensitivity of 0.64 and a specificity of 0.81 for renography. The study confirms an over-representation of scars judged from scintigrams, which calls for further investigation of scar formation detection.