One of the prerequisites for the implementation of modern criminal policy of the Republic of Moldova is the strict observance of one of its fundamental principles - the principle of legality. Huge impact on quality of this principle renders the presence of estimated concepts (elements) in the criminal legislation. It renders a huge number of problems arising in practice and in scientifi c fi elds of legal activity. The main purpose of this article is launching the theory of estimated signs in national criminal doctrine. We analyzed multiple points of view about the concept, traits and species of estimated signs in the criminal law and then we formulated our own view of these subjects. Hope that this article will be a good beginning for a multispectral research of estimated signs in Republic of Moldova.