The temperature distribution on the surface of the brain is described in detail for the first time both in the zone of projection of the nidus and in the zone of the relatively intact cortex at the stage before tumors of various histological nature are removed. The qualitative and quantitative post-stimulus characteristics are described for the thermal reactions in projection of the nidus in the near-tumor (peritumoral) zone and in regions far from the nidus on the surface of the dura mater and the cortex in patients with various histological types of tumors. The data concerning the variation of the thermal patterns in response to a cold test are analyzed.