  We analyze the potentiality of hadron colliders to search for large extra
dimensions via the production of photon pairs. The virtual exchange of
Kaluza--Klein gravitons can significantly enhance this processes provided the
quantum gravity scale ($M_S$) is in the TeV range. We studied in detail the
subprocesses $q \bar{q} \to \gamma \gamma$ and $g g \to \gamma \gamma$ taking
into account the complete Standard Model and graviton contributions as well as
the unitarity constraints. We show that the Tevatron Run II will be able to
probe $M_S$ up to 1.5--1.9 TeV at 2$\sigma$ level, while the LHC can extend
this search to 5.3--6.7 TeV, depending on the number of extra dimensions.
