Let A be a power-associative
ring, and suppose that for each a ∈ A there exists an integer n = n(a) > 1
such that an= a. Such a ring A is called a periodic ring. In this paper the
structure of all simple periodic rings of characteristic not 2 or 3 is determined.
This solves a problem posed by Osborn [Varieties of Algebras, Advances in
Mathematics, to appear]. It follows from these results and from Osborn’s that every
flexible periodic ring with no elements of additive order 2 or 3 is a Jordan
ring.