  In this work, we construct traversable wormhole geometries in the context of
f(R) modified theories of gravity. We impose that the matter threading the
wormhole satisfies the energy conditions, so that it is the effective
stress-energy tensor containing higher order curvature derivatives that is
responsible for the null energy condition violation. Thus, the higher order
curvature terms, interpreted as a gravitational fluid, sustain these
non-standard wormhole geometries, fundamentally different from their
counterparts in general relativity. In particular, by considering specific
shape functions and several equations of state, exact solutions for f(R) are
found.
