Our review of pediatric urinary tract ultrasonograms over a period of two and one-half years resulted in a catalog of pitfalls. Cases included normal scans mistaken for abnormal and vice versa. These erroneous diagnoses stemmed from the inappropriate selection of the primary imaging test, improper timing of the ultrasonogram, errors of commission or omission in performance of the scans, and improper interpretation of the findings. For ease of reference, the pitfalls are grouped under bladder, ureters, and kidney with emphasis on the first two which are common sources of error.