The characteristics of the adhesions of polyimide to silicon and to polyimide and the autohesion of a polyimide blend have been investigated. As found, the peel strength of pyromellitic dianhydride-4,4 prime -oxydianiline (PMDA-ODA) on silicon can be greatly improved by blending with 20 or 40% benzophenone tetracarboxylic dianhydride-p-phenylene diamine (BPDA-PDA). Exposing in air for a 2 day period resulted in a serious deterioration in adhesion for the pure PMDA-ODA system, while in no deterioration for the blend systems. Regardless of adhesion or autohesion, the resulting peel strength decreased markedly with the increase of the curing temperature. It was also found that based on the same curing temperature the diffusion of NMP is much faster in the film of PMDA-ODA than in the blend containing 20% BPDA-PDA. Beside curing temperature, imide-to-imide compatibility seems to play an important role in affecting the adhesion characteristics.