This article analyzes some problematic issues regarding the collection, admissibility and assessment in criminal proceedings of digital evidence resulting from covert surveillance, within the scope of the digital era, from a comparative perspective and based on the Spanish experience. To this end, some concepts and characteristics of the digital evidence are presented and some problems that this kind of evidence brings to criminal proceedings are presented. Then, the implications of how digital evidence is obtained, admitted and assessed when obtained by means of covert surveillance are analyzed. Finally, the concluding thoughts on the subject are presented. © 2021 Instituto Brasileiro de Direito Processual Penal. All rights reserved.