Diverse effects of temperature are well-known, from global warming to effects on biochemical reactions. Politically global warming has become a major issue. Body temperature is controlled in a narrow range to maintain normal cellular function. A few degrees change of body temperature impacts significantly on physiological response. The article describes the critical and significant impact of the temperature on medical science research within a microenvironment; on physiological effect of a cell, on conformation of a protein, and on possible benefit of a pathogen, thus urging more attention and research to the temperature effects in research not only on the interpretation of biological results cautiously and on drug development, but also on development of diagnostic reagents.