Drawing experiments have been performed to Point Out the fibrillar nature of Nafion membranes. The structure evolution upon drawing was monitored by small-angle X-ray scattering and small-angle neutron scattering (SAXS and SANS). The spectra were analyzed within the q-range 0.02-0.5 angstrom(-1) corresponding to a length scale larger than the fibril diameter, which is in the order of 4 nm. This q-range includes the so-called ionomer peak, analyzed as the peak of the structure factor and correlated to the average distance between the polymer fibrils. A basic deformation model of a fibrillar system is proposed to simulate the peak evolution. The other scattering feature treated in this paper is the power law of the scattering curve at low q analyzed considering a cylinder form factor, which is consistent with a fibrillar Structure.