  Starting from a QCD inspired bilocal quark interaction we obtain a local
effective meson lagrangian. In contrast to previous local (NJL-like)
approaches, we include nonlocal corrections related to the finite meson size
which we characterize by a small parameter. After bosonization using the
heat-kernel method we predict the structure coefficients of the
Gasser-Leutwyler $p^4$-lagrangian up to first order in this parameter. The
modifications for the $L_i$ coefficients are typically of the order 10-20\%,
except for $L_5$, where we find a stronger nonlocal influence.
