The article presents a comprehensive study of the subject of evidence in criminal proceedings involving evasion of serving a sentence. It is substantiated that the effectiveness of the educational function of criminal law depends directly on the actual execution of the imposed sentence, while evasion of serving it nullifies the achievement of the goals of criminal liability and undermines the authority of justice. On this basis, the structure of the subject of evidence is analyzed, taking into account the specifics of the components of criminal offenses provided for in Articles 389, 390, and 391 of the Criminal Code of Ukraine. It was established that the subject of proof in this category of proceedings includes not only the general circumstances defined by criminal procedural legislation but also additional elements, in particular the legal prerequisites for the emergence of the obligation to serve the sentence, the fact of the person’s awareness of its conditions, the presence of a real possibility of fulfilling the assigned duties, as well as the intention to fail to fulfill them. It was concluded that systematizing the elements of the subject of proof in cases of this category provides a basis for increasing the effectiveness of the pre-trial investigation and the formulation of forensic recommendations to counteract evasion of serving the sentence.