  In this letter we compute the exact effective superpotential of {\cal N}=1
U(N) supersymmetric gauge theories with N_f fundamental flavors and an
arbitrary tree-level polynomial superpotential for the adjoint Higgs field. We
use the matrix model approach in the maximally confinig phase. When restricted
to the case of a tree-level even polynomial superpotential, our computation
reproduces the known result of the SU(N) theory.
