Abstract To stop further increase of health care cost, the German government successively changed the regulatory framework including the reimbursement policies of hospitals. One of the major innovations is the lump-sum compensation of in-patient treatments based on Diagnosis Related Groups (DRGs). Since the implementation of the DRG-system in 2004, clinics are no longer being paid per day of performed services for each treated patient, but based on the syndrome/diagnosis of the respective patient. Compared to the former hospital and nursing charges, that were identical each day of performed services, DRGs now lead to different economical incentives for hospitals. From now on, hospitals need to utilize their resources much more efficiently in order to reduce waiting and treatment time of patients as well as to minimize cost per case. Mandatory for the accomplishment of those objectives is the quality of processes, meaning the efficiency and effectiveness of each process step that needs to be performed during patient treatment. In order to reduce the length of stay of patients as well as to reduce the cost for treatment, hospitals need appropriate tools and methods. The dynamic behavior of complex clinical processes in process optimization studies can only be modeled, analyzed and optimized with adequate, well performing simulation systems. Among others, those simulation systems shall provide a validated process framework for modeling and simulating clinical processes, comprising re-usable and executable building blocks. This is basis for comparisons of accomplished results, for instance in benchmark studies. On the other hand, the length of time for the development of simulation models can be drastically reduced by using standardized and re-usable building blocks. In this thesis a validated process framework was developed with the simulation system MLDesigner. This process framework comprises standardized building blocks for rapid modeling and simulation of hospital processes. Those building blocks are modularized, structured in pre-defined libraries of MLDesigner and named after the respective clinical process step. Selected clinical care paths were the basis for the development of the process framework. The developed building blocks were utilized for modeling, simulating and optimizing the processes of a cancer treatment center. As part of the process optimization study a significant reduction of patients’ waiting times was achieved. The process framework represents the concrete approach for standardization of modeling and simulation of clinical processes. Due to its modular set-up the process framework can be added and extended by additional processes at any time. The existing building blocks can be utilized for further simulation studies, e.g. as the basis for system design or the optimization of the integration of different sectors of the healthcare environment, i.e. integration of processes between doctors in private practices, hospitals and rehabilitation cent