  We show that a corpuscular description of gravity can lead to an inflationary
scenario similar to Starobinsky's model without requiring the introduction of
the inflaton field. All relevant properties are determined by the number of
gravitons in the cosmological condensate or, equivalently, by their Compton
length. In particular, the relation between the Hubble parameter $H$ and its
time derivative $\dot H$ required by CMB observations at the end of inflation,
as well as the (minimum) initial value of the slow-roll parameter, are
naturally obtained from the Compton size of the condensate.
