The child's testimony is a central part of investigating child sexual abuse. Many episodes of abuse do not leave physical signs. Forensic examiners and pediatricians and psychiatrists, and psychologists must be prepared to interview the child and obtain their description of the attack properly to get reliable evidence for the punishment of the crime. Based on medical literature research, the authors discuss the procedures adopted in Brazil after the enactment of Law 13431 of 2017, which establishes the obligation of "protected listening" to child victims of sexual abuse in the criminal process, as well as the justifications that lead the experts to consider the child testimony/disclosure about the abuse as vital evidence to convict the perpetrators in the courtroom.