Polymer thin films have generated much interest because of their increasingly important role in technological applications ranging from protective coatings to various organic material based devices. Polymer films deposited by vacuum evaporation often exhibit physical properties that differ substantially from intrinsic bulk behavior. After a comprehensive review of methods for deposition of thin polymer films in vacuum, we present our own results in this field. The main attention is paid to effect of PTFE, PCTFE and PE decomposition during thermal and electron beam heating and to the secondary polymerization of the decomposition products condensed on a substrate. The best results are obtained by using the electron beam initiation of the secondary polymerization. Variable parameters are the electron beam power, the condensation temperature, the current density of the electrons and their energy. The book provides a timely overview of a current state of knowledge in use of polymer thin film deposited in vacuum for important technological applications. It was written for both academic and practicing scientists interested in studying and application of polymer thin films.