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 observational constraints can be satisfied provided that the Chaplygin scale and the inflaton mass are smaller than 6.9 \times 10 ^ { -3 } ~ { } M and 4.7 \times 10 ^ { -6 } ~ { } M , respectively , where M ^ { 2 } \equiv ( 8 \pi G ) ^ { -1 } is the reduced Planck mass .