Thermomechanical and rheological properties of epoxy blends modified with different percentages of a hyperbranched polymer have been reported. The addition of the hyperbranched modifier did not alter the rheological behavior of the blend. This effect is particularly advantageous for some composite manufacturing techniques because it allows for the establishment of low viscosity during processing. Morphological development was studied under curing by hot stage microscopy. The cryo-fractured surfaces of the cured samples were analyzed by scanning electron microscopy. The morphological analysis showed that the blends did not phase separate at any modifier percentage. This result was further supported by dynamic mechanical testing (DMTA) on cured samples. In fact, DMTA showed a single relaxation peak for all the formulations studied. The dynamic testing was also used to assess the damping properties of the systems. The blends of this study were also compared with similar systems modified with poly(epsilon-caprolactone), which were the subjects of a previous article. POLYM. ENG. SCI., 48:2382-2388, 2008. (C) 2008 Society of Plastics Engineers