The objective of the present paper is to investigate the linear viscoelasticity of diluted suspension of MWNT spread in PDMS. Specifically, we focus our attention on both the CNT relaxation in semidilute conditions and the concept of percolation threshold for such system. Finally, the results, and mainly the concentration dependence of the zero-shear viscosity and mean relaxation time, will be discussed within the Doi−Edwards theory framework on molecular dynamic of rigid rods in a semidilute regime.