Three bisphenol A diphthalimide bisbenzoxazine monomers were successfully synthesized through a two-step procedure. First, a new bihydric phenol, bishydroxyphenyl bisphenol A diphthalimide, was prepared from bisphenol A dianhydride and 4-aminophenol. Then, different bisphenol A diphthalimide bisbenzoxazine monomers were synthesized from bishydroxyphenyl bisphenol A diphthalimide, paraformaldehyde, and various amines, such as aniline, allylamine, and 3-aminophenylacetylene. The chemical structures and compositions of the novel monomers were identified by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, and elemental analysis. The curing behavior of the three monomers after various thermal treatments was investigated by differential scanning calorimetry and Fourier transform infrared analysis. The polybenzoxazines from the three monomers had excellent high-temperature properties demonstrated by dynamic mechanical analysis. The thermal stabilities of the three polybenzoxazines were also studied by thermogravimetric analysis. The results revealed that the 5 and 10% weight loss temperatures were as high as over 360 and 405 degrees C, respectively, and the char yields at 800 degrees C were 41 to 61%, respectively. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2778-2787, 2011