All the living things, from single-cellular to multi-cellular organisms, are always exposed to certain environmental conditions. Sometimes, the environmental conditions are optimum for living, while the environment is very often harsh for the organisms, which is recognized as stress. During the processes of evolution, the organisms have developed various molecular mechanisms to protect themselves against the different environmental stresses. The collection of four papers in this issue presents timely developments in studies on the molecular mechanisms responding to environmental stresses such as cold temperature and DNA damage stress.