As a result of their continuous infl uence on social and, thus, criminal activity, both criminal law and criminal procedure, become interested in computers, data storage devices and assimilated technical means. However, the single stipulation is not enough for the use of data storage devices in criminal cases to be effi cient. It involves two other basic aspects: the prior admissibility by law of this kind of means of evidence and the later admissibility by its general and special requirements. This article will try to underline the major need of this two steps admissibility determination activity of data storage devices in criminal cases.