Rheological behavior of dynamically and statically vulcanized blends of isotatic Polypropylene (PP) and 20% wt Styrene-Butadiene-Styrene block copolymer (SBS) was studied with reference to the effect of extrusion conditions, curing agents (sulphur, peroxide) and curing times. All blends showed pseudoplastic behavior. When using sulphur, a slight increase on melt viscosity was observed, showing no differences with vulcanization method or with pre-vulcanization time. With peroxide, melt viscosity changed drastically. Dynamically vulcanized blends with sulphur showed a noticeable rise on elongation at break as well as on toughness while those statically vulcanized showed very low values on these properties.