  We address the problem of rationalizing the pattern of fermion masses and
mixings by adding a nonabelian flavor symmetry in a grand unified framework.
With this purpose, we include an A4 flavor symmetry into a unified
renormalizable SUSY GUT SU(5) model. With the help of the "Type II Seesaw"
mechanism we are able to obtain the pattern of observed neutrino mixings in a
natural way, through the so called tribimaximal matrix.
