Proper function of the cardiovascular system is indispensible to human survival. However, this system is dominated by complex interactions between different physiological processes and control mechanisms. A structured analysis and a mathematical description of this system can provide more insight, and a computer-based simulation of dynamic processes in the cardiovascular system could be applied in numerous tasks. This article gives a review of different approaches to cardio-circulatory modeling and discusses methodological aspects and fields of application for several classes of models.