Micropercutaneous nephrolithotomy (microperc) is the end point percutaneous nephrolithotomy (PCNL) technology for the present. In routine PCNL surgery, use of an Amplatz sheath is an important step, but in this technique, there is no Amplatz sheath. Some problems during surgery may occur because of the lack of an Amplatz sheath, which provides a tract between the skin and the collecting system. Therefore, we describe the smallest Amplatz sheath (6.6F) that is compatible with the microperc instrument and can be used during percutaneous surgery, especially in preschool pediatric patients.