This paper presents an application of the MLFMA to the analysis of conformed and finite-sized multilayered periodic structures modeled by parametric surfaces. Using these surfaces, the discretization, basis and test functions are conformed to any curved surface, with the advantage of an exact representation of the geometry. Using MONURBS [1], a moment method code, the scattering field of several samples points over the surface are obtained, so the reflection and transmission coefficients can be calculated. This method has been tested in several periodic structures achieving good results.