  We analysed ASAS-3 photometry of bright early-type stars with the goal of
finding new Beta Cephei stars. We were particularly interested in stars that
would be good for seismic analysis, i.e., stars that (i) have a large number of
excited modes, (ii) show rotationally split modes, (iii) are components of
eclipsing binary systems, (iv) have low-frequency modes, that is, are hybrid
Beta Cephei/SPB stars. Our study was made with a homogeneous sample of over
4100 stars having MK spectral type B5 or earlier. For these stars, the ASAS-3
photometry was analysed by means of a Fourier periodogram. We have discovered
103 Beta Cephei stars, nearly doubling the number of previously known stars of
this type. Among these stars, four are components of eclipsing binaries, seven
have modes equidistant or nearly equidistant in frequency. In addition, we
found five Beta Cephei stars that show low-frequency periodic variations, very
likely due to pulsations. We therefore regard them as candidate hybrid Beta
Cephei/SPB pulsators. All these stars are potentially very useful for seismic
modeling. Moreover, we found Beta Cephei-type pulsations in three late O-type
stars and fast period changes in one, HD 168050.
