The hot-carrier microwave conductivity characteristics of the elemental semiconductors are reviewed. Significant features of the microwave incremental conductivity and also of the high-field microwave conductivity are critically analysed. These features are explained from simple physical considerations. Comparison is then made between the detailed theories and the experimental results. It is shown that most of the features of the microwave conductivity characteristics agree with those expected from theory. Some of the finer details of the characteristics which require further investigations are also indicated. © 1968.