Poly(benzyl methacrylate) (PBzMA)/epoxy thermoset blends of composition 5 to 25 wt% of PBzMA were prepared curing with 4,4′diaminodiphenylmethane (DDM), to study the influence of composition on the morphology and dynamic-mechanical properties of the blends. The cured blends are phase separated in PBzMA-rich phase and epoxy rich-phase. As the PBzMA content increases, the morphology evolves from nodular, to combined and to totally inverted. The analysis of the α-mechanical relaxations indicates that the glass transition temperatures (Tg) of PBzMA and of epoxy in the blends are different from the neat polymers, this is related to a noncomplete phase separation on curing. The profiles of the loss modulus-temperature curves are correlated with the change in morphology that appears increasing the PBzMA content. The storage modulus-temperature curves are highly dependent on the morphology of the samples. The storage modulus-composition dependence is predicted using several models for two phase composites. POLYM. ENG. SCI., 50:1820–1830, 2010. © 2010 Society of Plastics Engineers