The histories and imaging results are presented in 10 children in whom errors had been made in the interpretation of early investigations. Ultrasonography may not detect either vesicoureteric reflux (VUR) or renal scars or inflammation. The reduced nephrogram or renal swelling following a first attack of acute pyelonephritis may not be recognised without renal measurement on an intravenous urogram. Renal scarring may be diagnosed incorrectly on the basis of functional defects of isotope uptake on a technetium 99m-dimercaptosuccinic acid study. In the absence of VUR, the micturating cystogram will not visualise the kidneys.