An algebraic curvature tensor is
called Osserman if the eigenvalues of the associated Jacobi operator are constant on
the unit sphere. A Riemannian manifold is called conformally Osserman if
its Weyl conformal curvature tensor at every point is Osserman. We prove
that a conformally Osserman manifold of dimension n≠3,4,16 is locally
conformally equivalent either to a Euclidean space or to a rank-one symmetric
space.