The article describes systems of prefabricated monolithic slabs (PMS) that have received the most widespread in Russia and in the world. The issue of reducing the weight of building structures is an important issue of structural science. Systems of the prefabricated monolithic constructions correspond to the modern trends, but require special attention and scrutiny. Analysis of advantages and disadvantages of the prefabricated monolithic slabs is shown in the article. In addition, the problems of use were identified and designated. It are required to study in detail for supporting free use of PMS in the buildings and structures.