  We review the nature of the oscillations of main-sequence and supergiant
stars of spectral type B. Seismic tuning of the interior structure parameters
of the $\beta $Cep stars has been achieved since three years. The results are
based on frequencies derived from long-term monitoring and progress in this
area is rapid. Oscillations in mid-B stars as well as Be stars are well
established by now, but we lack good mode identification to achieve seismic
modelling. We provide recent evidence of g-mode pulsations in supergiant B
stars. The spherical wavenumbers of their modes are yet unidentified,
preventing seismic probing of such evolved hot stars at present. Improving the
situation for the three groups of g-mode oscillators requires multi-site
long-term high-resolution spectroscopy in combination with either space
photometry or ground-based multicolour photometry. The CoRoT programme and its
ground-based programme will deliver such data in the very near future.
