  The neutral Kaon decays Ks->gamma gamma and Kl->pi0 gamma gamma are very
sensitive to higher order loop effects of Chiral Perturbation Theory (ChPT).
New measurements of the NA48 experiment show that ChPT contributions of O(p^6)
cannot be neglected in these modes. In addition a new measurement of the
related decay Kl->gamma gamma and an upper limit of the rate of Ks->pi0 gamma
gamma are presented.
