Three kinds of thermoplastic/thermosetting polyimide blends have been prepared using three kinds of commercially available soluble polyimides(AL1051, PI2080, Ultem) and N, N′ – (methylenedi-p-phenylene) bismaleimide(BMI). The DSC thermograms of the polyimide blends showed exotherms at higher temperatures compared to BMI alone. The cure characteristics of the blends changed significantly according to the thermoplastic polyimide component. The fracture surfaces of PI2080 and Ultem blends, examined under a scanning electron microscope, showed distinct nodular morphological features. However, in the case of AL1051, which was derived from a aliphatic acid, this kind of phase separation was not observed. The mechanical properties of the blends were studied by using a thermomechanical analyzer. The blends yielded films with good mechanical properties even at high temperatures. The BMI component did not have any significant effect on the glass transition temperatures. However it showed improved mechanical properties at high temperatures. The blends were brittle compared with the thermoplastic polyimides. The tensile and electrical properties of the blends and their coefficients of thermal expansion were also studied.