The rheological behavior of miscible blends was studied through oscillatory shear measurements. Two miscible blends were selected to compare with athermal blending cases, i.e. the hydrogen bonding poly(4-vinyl phenol)/poly(ethylene oxide) (PVPh/PEO) blend and the weakly interacting polystyrene/poly(2,6-dimethyl-1,4-phenylene oxide) (PS/PPO) blend. The homopolymers and the blends were characterized over a wide experimental window using the time-temperature superposition principle. The horizontal shift factor, a(T), does not vary appreciably with composition for PS/PPO, whereas a strong compositional dependence is observed for the PVPh/PEO blends. Additions of up to 30 wt% of PEO to PVPh produce only minor changes in the value of rubber plateau modulus (G(N)(0)), while G(N)(0) increases steadily after this concentration. The G(N)(0) values follow athermal blending models [J. Polym. Sci., Part B: Polym. Phys. 25 (1987) 2511; J. Polym. Sci., Part B: Polym. Phys. 26 (1988) 2329] in the case of PS/PPO but not of PVPh/PEO. Values of eta(0b) for PVPh/PEO blends were estimated from weighed relaxation spectra. The three measured parameters, aT, Go and 770 show a turning point around 20-30 wt% of PEO, which corresponds to a 41-54 mol% of PEO, in correlation with the previously reported observation of a maximum in the deformation-induced uniaxial orientation behavior of PEO component near this composition [Macromolecules 32 (1999) 8509]. (C) 2003 Elsevier Science Ltd. All rights reserved.