The interfacial tension between molten, high molecular weight samples of polycarbonate and poly(methyl methacrylate) was measured using the imbedded fiber retraction (IFR) technique. A value of 1.44 +/- 0.16 dyn/cm was measured at 240-degrees-C. This value was obtained on commercial resins with zero-shear bulk viscosities and at a temperature typically encountered in the processing of blends and/or composites. Refinements to the IFR method were implemented which reduced the experimentation time. Consequently, measurements of the interfacial tension can now be routinely obtained in several hours for materials with zero-shear bulk viscosities on the order of 10(4) Pa s.