This book constitutes the proceedings of the 20th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems, MMB 2020, held in Saarbrücken, Germany, in March 2020. The 16 full papers presented in this volume were carefully reviewed and selected from 32 submissions. They are dealing with scientific aspects of measurement, modelling and evaluation of intelligent systems including computer architectures, communication networks, distributed systems and software, autonomous systems, workflow systems, cyber-physical systems and networks, Internet-of-Things, as well as highly dependable, highly performant and highly secure systems.