Self-prescribing or medicating 'by proxy' is not an autonomous, free and voluntary decision in the case of children. On the contrary, in this case it is based on the subjective interpretation of symptoms made by the mother or by a third person who is legally responsible for the minor. In our opinion, to analyse this situation is of great importance in order to know the determining factors, perceptions, and realities related to this problem.Our proposal is to perform a prospective observational study for analysing maternal and familiar determinant factors related to self-prescribing and self-medicating 'by proxy' in paediatrics. A validated survey was developed to be applied to mothers of children aged 0 to 14 who are users of the Paediatric Emergency Department in a hospital.A total of 1,714 mothers were recruited in a random period of time. This sample included 345 mothers who exclusively self-medicated their children (case group), and 1,369 mothers (control group) who did not meet this requirement. The overall percentage of medicating 'by proxy' was 32.8%. There is a significant association between self-medicating and educational level of the mother, the number of children, and the birth order among siblings. Neither maternal age nor social-occupational level are related to this problem. Most frequently used drugs include antipyretics and 'anticatharrals', usually administered as a monotherapy.Our results seem to indicate that the educational level and the parental experience acquired with previous children could generate the required confidence in parents to choose the medication by themselves. Almost 85% of these drugs come from the 'home first-aid kit.'