  We study the Seiberg-Witten curves for N=2 SUSY gauge theories arising from
type IIA string configurations with two orientifold sixplanes. Such theories
lift to elliptic models in M-theory. We express the M-theory background for
these models as a nontrivial elliptic fibration over C. We discuss
singularities of this surface, and write the Seiberg-Witten curve for several
theories as a subvariety of this surface.
