  We discuss chaotic inflation in the context of a phenomenological
modification of gravity inspired by the Chaplygin gas equation of state. We
find that all observationalconstraints can be satisfied provided the Chaplygin
scale is smaller than $6.9 \times 10^{-3} M$ and the inflaton mass is smaller
than $4.7 \times 10^{-6} M$, respectively, where $M^2\equiv(8 \pi G)^{-1} is
the reduced Planck mass.
