The linear viscoelastic properties of polystyrene polyethylene (PS/PE) blends have been investigated in the molten state. For concentrations of the dispersed phase equal to 30 vol %, the blends exhibited a droplet-matrix morphology with a volume-average diameter of 5.5 mu m for a 70/30 PS/PE blend at 200 degrees C and 14.7 mu m for a 30/70 PS/PE blend at 230 degrees C. Enhanced elasticity (G') for both blends, in the terminal zone, compared to the modulus of the matrix (PS and PE, respectively) was observed. This is related to the deformation of the droplets in the matrix phase and hence to the interfacial forces between the blend components. The results for these uncompatibilized blends are shown to be in agreement with the predictions of the emulsion model of Palierne. These predictions were used to obtain the interfacial tension between PS and PE, which was found to be between 2 and 5 mN/m at 200 degrees C and 4 +/- 1 mN/m at 230 degrees C. Independent interfacial tension measurements using the breaking-thread method resulted in a value of 4.7 mN/m and 4.1 mN/m at 200 degrees C and 230 degrees C for the respective blends.