To the Editor.— I am fascinated by the articles in the May 8th JAMA 1-3 in which the authors suggest that primary vesicoureteral reflux may be a familial hereditary disease transmitted genetically. It is certainly true that reflux is rare in blacks. However, reflux has some characteristics that make it very difficult to interpret the pedigrees. An as yet undetermined percentage of babies are born with reflux. Some continue to reflux for their lifetime, but others stop refluxing spontaneously without their reflux ever being discovered. Thus, in studying a family, if the mother and father have no reflux on their cystograms you cannot be certain that they did not have childhood reflux that healed spontaneously, and, therefore, they could be carrying the gene that is transmitting the reflux. Even in studying the children, one cannot be certain that those with normal cystograms did not actually have reflux earlier in life.