  We report on our determination of the values of the one and two loop low
energy constants appearing in the Chiral Perturbation Theory calculation of the
pi-pi scattering amplitude. For this we use a precise sum rule determination of
scattering lengths and slopes that appear in the effective range expansion. In
addition we provide new sum rules and the values for these coefficients up to
third order in the expansion. Our results when using only the scattering
lengths and slopes of the S, P, D and F waves are consistent with previous
determinations, but seem to require higher order contributions if they are to
accommodate the third order coefficients of the effective range expansion.
