Dear EditorSir, the recent publication on hyperbilirubinemia and pelvicaliceal dilatation is very interesting. Akil et al concluded that “hyperbilirubinemia might not have a direct effect on outcome of the pelvicaliceal dilatation [1].” There were several problems on this work that limited the conclusion. The few subjects and no control of confounding factor (such as genetic disorders that can cause hyperbilirubinemia) were not controlled. Indeed, although pelvicaliceal dilation can cause urinary tract infection and possible further hyperbilirubinemia, it is not the direct one-step relationship [2].