The viscoelastic properties such as storage modulus (E′), loss modulus (E”) and damping (tan δ) of unfilled and silica-filled blends of natural rubber (NR) and ethylene-vinyl acetate copolymer (EVA) have been evaluated. The blends were crosslinked by a mixed system consisting of accelerated sulfur and peroxide. The tan δ values of unfilled blends showed two transitions corresponding to EVA and NR phases. This indicated that the blends are immiscible. The damping curves of EVA and EVA-rich blends possess three distinct regions: a rubbery plateau, a melt transition, and a viscous plateau. It is seen that the addition of silica decreased the tan δ values of the samples substantially except that of NR, where a slight increase in tan δ values can be observed at high temperatures. The sharp decrease in tan δ in filled EVA and EVA-rich blends is associated with the decrease in crystallinity of the EVA phase due to the presence of filler. Addition of silica filler increased the storage and loss modulus of all the samples.