Good question! But no, we advise you not to use Oopsie Heroes in combination with a diaper. Here is why: when you place the sensor on the outside of a diaper it can’t detect the urine, placing it on the inside would block the sensor signal. Next to that, experts advise people to not use diapers anymore as soon as you start using a bedwetting alarm. The learning curve of the child will be much less since the diaper makes the child feel too protected and he or she won't notice when the diaper gets wet. So it’s better not to use diapers.