2640 20160701171708.0 ASTROimport-797 De Cat, P. 2006 A new era of asteroseismology: hot stars To fully understand the evolution of stars, detailed information on the processes acting in the stellar interior is needed. Since the stellar interior is not directly accessible, asteroseismologists thankfully use the indirect information contained in stellar oscillations to probe the stellar interiors. There are two families of modes carrying information of different parts of the stellar interior: pressure modes (p-modes; mainly propagating in the envelope) and gravity modes (g modes; mainly propagating in the core). For a unique asteroseismic modelling, a large number of well-identified modes are needed. Different classes of oscillating stars are found across the Hertzsprung-Russell diagram. The β Cephei and δ Scuti stars (pulsating in low order p and g modes with periods of the order of hours) and the slowly pulsating B and γ Doradus stars (pulsating in high order g modes with periods of the order of days) are situated along the upper part of the main sequence. In this talk, we will outline their seismic potential and highlight their most important seismic results based on well-chosen examples. It becomes clear that long-term (and preferably multi-site) campaigns are needed to overcome the obstacles of ground-based observations. On the other hand, the high-quality data delivered by the MOST satellite has already led to important results for main-sequence pulsating stars. The future of asteroseismology is therefore bright with upcoming space missions like CoRoT. IAU Joint Discussion 17 2006 19 http://esoads.eso.org/abs/2006IAUJD..17E..19D published in NONREF