  I review the recent calculations and current status of the hadronic
light-by-light scattering contribution to muon g-2. In particular, I discuss
the main results obtained in a recent work together with Eduardo de Rafael and
Arkady Vainshtein where we came to the estimate a^{\rm HLbL}_\mu = (10.5 +-
2.6) x 10^{-10}. How the two-photon physics program of low energy facilities
can help to reduce the present model dependence is also emphasized.
