  We present the results of a first campaign of radio continuum observations
toward supergiants with spectral types in the range O8 - B3. Three targets out
of twelve were detected with the ATCA and the VLA. The measured fluxes and the
upper limits yielded values of the stellar mass-loss rates dM/dt and the wind
efficiencies. The comparison of predicted and derived values of dM/dt shows a
good agreement.
