oral evidence based on statements of fact by the accused (confession), witness (testimony) or plaintiff (oath) has gained relative credibility according to social developments. These evidences have an important role in the proceedings in order to show the reality directly and at a lower cost. Against, the scientific evidence that is based on the discovery of facts, have gained more and more credibility. Sometimes oral evidences conflict with scientific evidences, and the the fact that is made by the accused or witness or the plaintiff is different from the fact that is shown by scientific evidences. If scientific evidence has a certain proving of fact or if we have Subjectivity of Evidence for oral evidence, the conflict can be resolved easily. Regarding the subjectivity of oral evidence, how is the conflict resolution in the assumption that scientific evidence did not show the invalidity of oral evidence? Should we prefer scientific evidence and say that oral evidence are not valid if they don’t prove beyond reasonable doubt? Or we should prefer oral evidence due to lack of knowledge to the contrary? By stating the relationship between oral and scientific evidence, this article has examined this issue from the perspective of jurisprudence, law and judicial opinions of Tehran judiciary