Diaper dermatitis is one of the most common problems in childhood, from newborns to older children. The combination of non-breathable diapers, together with foils that adhere tightly to the baby's delicate skin, creates an ideal environment together with urine and stool for the multiplication of various types of bacteria and yeast. But of course we must not forget to rule out other general diseases. In the case of an unclear diagnosis, a smear from the affected area accurately identifies the cause of the problem, and then the treatment is focused on restoring the normal flora by frequent diaper changes, increased hygiene, and appropriate treatment according to the result of the smear.