In hyperthermia cancer treatments, a crucial problem is keeping the temperature of the normal tissue surrounding the tumor below a certain threshold so as not to cause damage to the tissue. Thus, obtaining a temperature field of the entire treatment region is important to control the process. In this study we develop a model and a numerical method for obtaining an optimal temperature distribution in a triple-layered skin structure embedded with multi-level blood vessels. The heat is induced by electromagnetic (EM) radiation. The dimensions and blood flow of multi-level blood vessels are determined based on the constructal theory. (c) 2006 Elsevier Ltd. All rights reserved.