  The impact of FUSE upon the fundamental parameters of OB stars and Wolf-Rayet
stars is reviewed. The stellar wind signatures available in the far-UV provide
us with important additional diagnostics of effective temperature. Together
with improved non-LTE stellar atmosphere models allowing for line blanketing
and stellar winds, this has led to a downward revision in the spectral
type-temperature calibration for O stars versus Vacca et al. (1996) In
addition, the Lyman continuum ionizing fluxes from O dwarfs are compared with
previous calibrations of Panagia (1973) and Vacca et al. We also discuss
mass-loss rates in OB stars, such that agreement between recent theoretical
predictions (Vink et al. 2000, 2001) and observations of O supergiants is
possible, solely if winds are clumped in the far-UV and H-alpha line forming
regions, as favoured by line profile comparisons for PV 1118-28 (early to mid
O) or SIV 1062-1073 (late O to early B) in FUSE datasets. In contrast, B
supergiant wind strengths are predicted to be much higher than observations
indicates, especially if their winds are also clumped. Finally, significant
upward revisions in wind velocities of very late WN stars are indicated by NII
1085 resonance line observations, plus elemental abundances in OB and WR stars
are briefly discussed.
