Unitarity and K$_{L}$ --> $\pi^{0}\gamma\gamma$

We discuss the rare decay K(L) --> pi0gammagamma. Although the recently measured 2gamma-invariant-mass distribution is in quite good agreement with the lowest-order chiral perturbation theory prediction, there seems to be a discrepancy with the calculated branching ratio. We extend the previous computations to next-to-leading order, O(p6). The two dominant mechanisms at this order are emphasized: the two-pion intermediate state and vector meson exchange.