The high-temperature limit of the three-graviton vertex function is st
udied in thermal quantum gravity, to one-loop order. The leading (T4)
Contributions arising from internal gravitons are calculated and shown
to be twice the ones associated with internal scalar particles, in co
rrespondence with the two helicity states of the graviton. The gauge i
nvariance of this result follows as a consequence of the Ward and Weyl
identities obeyed by the thermal loops, which axe verified explicitly
.