Blends of high density polyethylene (HDPE) and acrylonitrile butadiene rubber (NBR) were prepared by a melt blending technique. Dynamic mechanical analysis revealed that elastic modulus has a strong dependence on blend ratio. Loss factor peaks increase with increase in rubber content. Pure components exhibit single Tg whereas two Tgs can be observed in the blends indicating incompatibility between the constituents. Loss modulus data also give similar information. The addition of compatibilizer has only a marginal effect on tan δ peak corresponding to the transitions in NBR. The elastic modulus values of the compatibilized blends are slightly higher than that of incompatible blends. In dynamically vulcanized blends the Tg due to α-relaxation of NBR is increased in blends containing a high concentration of rubber phase. In filled blends the elastic modulus showed significant increase over unfilled system. Also, the damping factor is enhanced by filler incorporation indicating that such materials could find application in vibration dampers. The suitability of various theoretical models in predicting the blend moduli is examined. The Takayanagi model fits well with the experimental data in unfilled blends.