The aim of this project is to generate evidence and support tactical decisions in operating room management through new mathematical models. In particular, this project is focused on working with hospitals in two different health care systems, Portugal and Germany, and developing optimization methods to increase efficiency by assigning OR time to specialties considering multiple criteria sourced by 1) stakeholders’ preferences and perspectives, 2) up and downstream units’ capacity and workload, and 3) scheduling strategy.  Simulation models will be designed to evaluate the performance in real-life settings.