In this seminar, an overview of the utility of studying non-radial non-adiabatic oscillations of stars such as $\delta$ Scuti, $\beta$ Cephei and Slowly Pulsating B stars will be given, with a particular attention on the problem of mode identification. Then I will present in more details the particularities of the non-adiabatic code I have written, which is mainly the special care given to the modelling of the pulsation in the atmosphere.