This work was divided into three parts. First, high-impact polystyrene (HIPS) was submitted to a series of extrusion cycles with the objective of evaluating the consequent variations in its thermal and mechanical properties. The results showed slight variations in both the thermal and mechanical properties of HIPS. Second, degraded HIPS/styrene-ethylene-butylene-styrene (SEBS) blends and degraded HIPS/styrene-butadiene rubber (SBR) blends were prepared to evaluate the influence of the elastomeric concentration on the polymer's properties. The incorporation of SEBS or SBR allowed the recovery of the initial properties shown by virgin HIPS. Finally, blends of degraded HIPS with 2 wt % SEBS or SBR were extruded through four cycles. The mechanical properties remained constant with 2% SEBS added, whereas the mixtures of HIPS with 2% SBR showed an increase in the tensile strength as the number of extrusion cycles increased. The Vicat softening temperature decreased in both cases. The use of differential scanning calorimetry permitted the observation of differences in the crosslinking reactions of different samples as a function of the number of extrusion cycles. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 574-581, 2011