  The $\gamma\gamma \to \pi^0 \pi^0 \pi^0$ and $\gamma\gamma \to \pi^+ \pi^-
\pi^0$ amplitudes are discussed in the general context of Chiral Perturbation
Theory (ChPT) to $O(p^6)$. Chiral loops are found to play a major role. This
makes these processes a good test of ChPT, mainly in its anomalous sector. We
correct earlier numerical results at tree level and determine the one-loop
results as well.
