  We study steady state winds from compact objects in the regime where the wind
velocity at infinity is ultra-relativistic. This may have relevance to some
models of Gamma-Ray-Bursts (GRB's). Particular attention is paid to the case
where neutrinos provide the heating. Unless the neutrino luminosity is very
large, L>10^{54} erg/s, the only allowed steady state solutions are those where
energy deposition is dominated by neutrino-antineutrino annihilation at the
sonic point. In this case, the matter temperature near the neutron star surface
is low, less than 1MeV for typical neutrino luminosities. This is in contrast
to the case for sub-relativistic winds discussed in the context of supernovae
where the matter temperature near the neutron star approximates the temperature
characterizing the neutrinos. We also investigate the setting of the neutron to
proton ratio (n/p) in these winds and find that only for large (>10 MeV)
electron neutrino or electron anti-neutrino temperatures is n/p entirely
determined by neutrino capture. Otherwise, n/p retains an imprint of conditions
in the neutron star.
