  We forecast the constraints on modified theories of gravity from the cosmic
microwave background (CMB) anisotropies bispectrum that arises from
correlations between lensing and the Integrated Sachs-Wolfe effect. In models
of modified gravity the evolution of the metric potentials is generally altered
and the contribution to the CMB bispectrum signal can differ significantly from
the one expected in the standard cosmological model.We adopt a parametrised
approach and focus on three different classes of models: Linder's growth index,
Chameleon-type models and f(R) theories. We show that the constraints on the
parameters of the models will significantly improve with future CMB bispectrum
measurements.
