While ne in vivo modeling of the heat exchange processes is indeed extremely complex, the mathematical theory of the control system oers easy-to-manage tools for modeling feedback processes, which are the basis of homeostatic controls. ese tools are oen used in bioengineering to model biological functions as in the devices for automatic glucose control or pace maker. Very few studies combining thermal imaging data and automatic system control theory are available. In this chapter, we provide examples of such an approach for two important pathologies: Raynaud’s phenomenon and varicocele.