Let R be a simple
anti-flexible ring of characteristic distinct from 2 and 3. Anderson and Outcalt have
proved that R+ is a commutative associative ring. The same authors have also shown
that a commutative associative ring P of characteristic not 2 gives rise to a simple
anti-flexible ring provided P has a suitably defined symmetric belinear form on
it. The purpose of this paper is to give an explicit construction of such a
symmetric bilinear form and determine the suitable commutative associative
rings.