A classification of screens, which covers structures applied in industry, and also new solutions of highly efficient high-tech screens tested in pilot-plant scale is presented in the paper. The last screen classification published in literature comes from Wessel (1963) and is not valid any longer. Therefore, in this paper a new classification of screens is shown which includes the latest achievements in this field and excludes old screens that are not offered by machinery producers any longer. In the construction of screening machines there are certain design solutions which have been considered the most appropriate now. In the case of screens with a linear flow of screened material through the machine, these are the screens with a drive with two synchronised rotary vibrators. The construction enables different trajectories of riddle vibrations. In the case of spiral flow of screened material on the sieve, there are wobbling caisson screens which actually have dominated this machine class. Other screening machines constitute small part of all produced screens and complete the two main classes mentioned above. All most important screening machines used in the national economy of a developed country will be presented in this paper.