The thermal anomalies in injection laser diodes, effected by the changing of temperature are reviewed. Case assembly and mounting methods are analysed in respect of cooling. Methods for measurement of temperature of laser diodes are reviewed. Methods developed for measurement of thermal transients and compensation of their effects are showed. Knowing the mounting process and materials, and on the basis of measurement results we can choose the method of the regulating the cooling (for example in the case of thermoelectric cooling).