  In early type stars the ultraviolet spectral region is important for several
reasons. Firstly, since the majority of the total flux is emitted here, it
provides a rather sensitive indicator of a photospheric temperature and
luminosity. Secondly, the UV spectra are dominated by lines of the iron-group
elements, which cause the origin of the opacity bump at temperature $2 \times
10^5$ K, where the classical $\kappa$ mechanism drives pulsations of $\beta$
Cep stars. Consequently, the position of the instability domain in the HR
diagram strongly depends on the metal abundance (Pamyatnykh 1999).
  We derive stellar parameters (metallicity, [m/H], effective temperature,
$T_{\rm eff}$, stellar diameter, $\theta$) and interstellar extinction,
$E(B-V)$, for all $\beta$ Cep stars observed by {\it International Ultraviolet
Explorer} satellite. The parameters are derived by means of an algorithmic
procedure of fitting theoretical flux distributions to the low-resolution IUE
spectra and optical spectrophotometric observations. The errors are estimated
by using the bootstrap method (Press et al. 1992). We also show some examples
of high-resolution HST/GHRS spectra for one $\beta$ Cep star: $\gamma$ Peg.
