The study addresses the issue of legal protection of an under-age person under Art. 185a–c of the Criminal Procedure Code in a Polish criminal trial. In this context, the author has analysed the following issues: the age in the context of the term “child” from the perspective of international, EU and Polish laws, the hearing of an under-age injured person as a witness and under-age witness only once and only if his or her testimony may be of significant importance for the resolution of the case (Art. 185a and b of the Criminal Procedure Code) and the conditions for a repeated hearing. Then the author has presented specific measures to protect the conduct of a hearing of a person injured by an offence under Art. 197 of the Criminal Code, i.e. rape; under Art. 198 of the Criminal Code, i.e. taking advantage of one’s vulnerability or disability in order to subject such a person to sexual intercourse or makes him/her submit to another sexual act; under Art. 199 of the Criminal Code, i.e. abuse of a relationship of dependence.