  We study brane configurations which correspond to field theories in four
dimension with N=2 and N=1 supersymmetry. In particular we discuss brane
motions that translate to Seiberg's duality in N=1 models recently studied by
Elitzur, Giveon and Kutasov. We investigate, using the brane picture, the
moduli spaces of the dual theories. Deformations of these models like mass
terms and vacuum expectation values of scalar fields can be identified with
positions of branes. The map of these deformations between the electric and
dual magnetic theories is clarified. The models we study reproduce known field
theory results and we provide an example of new dual pairs with N=1
supersymmetry. Possible relations between brane configurations and
non-supersymmetric field theories are discussed.
