A pilot numerical study is conducted to investigate whether a tumor located in the outermost layers of the brain is able to change power absorption and temperature increase in the head, when exposed to the field radiated by a cellular phone. Results show that absorption into the head tissues different from the tumor is barely affected by its presence. On the other hand, inside the tumor, tumor dielectric properties highly influence electromagnetic power absorption, while temperature increments are mainly affected by tumor thermal properties rather than dielectric properties. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1264-1267,2010; Published online its Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.2515