  In the framework of the chiral perturbation theory we computed two- and
three-loop corrections to the pion parton distributions which posses
$\delta$-function singularities at x->0. This calculation explicitly
demonstrates that in the region of small x ~ mpi^2/(4 pi F)^2 standard ChPT
breaks down and one needs resummation of all orders. We give an example of such
resummation.
