  We present the matrix elements for the semileptonic kaon decays
$K_{l2\gamma}$, $K_{l2l^+l^-}$, $K_{l2l'^+l'^-}$, $K_{l3}$, $K_{l3\gamma}$ and
$K_{l4}$ at next-to-leading order in chiral perturbation theory and compare the
predictions with experimental data. Monte Carlo event generators are used to
calculate the corresponding rates at DAFNE. We discuss the possibilities to
improve our knowledge of the low-energy structure of the Standard Model at this
and similar machines.
