  The Large Eddy Simulation (LES) approach is adapted to the study of plasma
microturbulence in a fully three-dimensional gyrokinetic system. Ion
temperature gradient driven turbulence is studied with the {\sc GENE} code for
both a standard resolution and a reduced resolution with a model for the
sub-grid scale turbulence. A simple dissipative model for representing the
effect of the sub-grid scales on the resolved scales is proposed and tested.
Once calibrated, the model appears to be able to reproduce most of the features
of the free energy spectra for various values of the ion temperature gradient.
