  The CP conserving amplitudes for the decays $K\to3\pi$ are calculated in
Chiral Perturbation Theory at the next-to-leading order. We present the
expressions in a compact form with single parameter functions only. These
expressions are then fitted to all available $K\to2\pi$ and $K\to3\pi$ data to
obtain a fit of the parameters that occur. We compare with the work of Kambor,
Missimer and Wyler.
