In recent years an increasing number of studies on thermophilic and hyperthermophilic proteins aiming to elucidate determinants of protein thermostability have yielded valuable insights about the relevant mechanisms. In particular, comparison of homologous enzymes with different thermostabilities (isolated from psychrophilic, mesophilic, thermophilic and hyperthermophilic organisms) offers a unique opportunity to determine the strategies of thermal adaptation. In this respect, the medium-sized amylolytic enzyme alpha-amylase is a well-established representative. Various studies on alpha-amylases with very different thermostabilities (melting temperature T(m) = 40-110 degrees C) report structural and dynamical features as well as thermodynamical properties which are supposed to play key roles in thermal adaptation. Here, results from selected homologous alpha-amylases are presented and discussed with respect to some new and recently proposed strategies to achieve thermostability.