We study brane configurations in the presence of orientifold six-plane
s. After deriving the curves for N = 2 supersymmetric SU(N-c) gauge th
eories with one flavor in the symmetric or antisymmetric representatio
n and Nf fundamental flavors, we rotate the brane configuration, reduc
ing the supersymmetry to N = 1. For the case of an antisymmetric flavo
r and less than two fundamental flavors, nonperturbative effects lead
to a brane configuration that is topologically a torus. Using the desc
ription of the orientifold six-planes as D-n singularities we discuss
the Higgs branches for N = 2 brane configurations with Sp/SO gauge gro
ups and the related N = 1 theories with tensor representations.