  We study the chaotic inflation in the context of a gravity theory where the
Friedman equation is modified, inspired by the polytropic gas equation of
state. It is seen that in the $n=1$ case for the polytropic index the inflaton
field at the end of inflation $\phi_e$, depends on the Planck mass, while for
$n\neq1$ it generally depends on the polytropic constant and mass of the
inflaton field.
