It is well established that food ingestion induces increased thermogenesis, but the site in man of this increased heat production is still not known. Recent data suggest that brown adipose tissue or the liver may have an important role in this phenomenon. Since recent research provides some evidence to suggest that activation of thermogenesis in a specific organ or tissue may determine increased skin temperature in the surrounding region, we have studied skin temperature in the dorsal interscapular and in the liver regions using infra-red thermography in groups of normal and obese subjects before and after administration of oral glucose. In a separate group of normal subjects we studied oxygen consumption before and after glucose administration. While oral glucose produced a clear increase in thermogenesis, no ascertainable variation was observed in body temperature and, therefore, of heat dispersion in any of the regions studied in either normal or obese subjects.