The study aims to shed light on the evidence of testimony consider that it is as one of the evidences of proof in the criminal case, the study will also discuss the extent of evidence of testimony in criminal trials and its relevance in the evidence. In order to achieve the desired objective of this study, the introductory chapter in this thesis was devoted to illustrating the concept of proof in general, its importance, and its methods. The researcher divided this thesis into two chapters, the first of which presents the nature of testimony as evidence of criminal proof in terms of definition, importance, characteristics and conditions, while in the second chapter the procedures for proof of testimony and assessment of its value were reviewed in order to answer the problem raised in this study. In this study, the researcher used the comparative method by comparing what was mentioned by the Omani legislator, and the Egyptian and Jordanian legislators referring to the judicial applications in this subject. Also, referring to the opinion of Islamic law in this context.