  We study the stationary and transient behaviors of the microemulsion phase
subjected to a shear flow. The system is described by a diffusion-convective
equation which generalizes the usual Cahn-Hilliard equation. Non-linear terms
are treated in a self-consistent approximation. Shear, first and second normal
stresses are calculated as momenta of the structure factor. Shear thinning is
observed in stationary conditions. After a newtonian regime at small values of
the shear rate, the excess viscosity decreases when the shear rate becomes of
the order of the inverse of the relaxation time of the system without flow. In
transient regimes, when the flow is applied starting from a quiescent state, we
find that the shear stress reaches a maximum before decreasing to a constant
value.
