  We analyze generalizations of two dimensional topological insulators which
can be realized in interacting, time reversal invariant electron systems. These
states, which we call fractional topological insulators, contain excitations
with fractional charge and statistics in addition to protected edge modes. In
the case of s^z conserving toy models, we show that a system is a fractional
topological insulator if and only if \sigma_{sH}/e^* is odd, where \sigma_{sH}
is the spin-Hall conductance in units of e/2\pi, and e^* is the elementary
charge in units of e.
