  We use type IIB brane configurations which were recently suggested by Hanany
and Zaffaroni to study four dimensional N=1 supersymmetric gauge theories. We
calculate the one loop beta function and realize Seiberg's duality using a
particular configuration. We also comment on the anomaly cancelation condition
in the case of chiral theories and the beta function in the case of chiral and
SO/Sp theories.
