AbstractPhosphorus‐containing polyimide resins were prepared by reacting benzophenone tetracarboxylic acid dianhydride with (3‐aminophenyl) methyl phosphine oxide (DAP). Copolyimides were also prepared using DAP and 4,2′,4′‐triaminobenzanilide (TAB) and tris(3‐aminophenyl) phosphine oxide (TAP) and pyromellitic dianhydride (PMDA). The homopolymer showed good thermal properties and little degradation below 400°C. The lapshear strengths of these polyimides depended on the backbone structure. Copolymerization improved thermal and mechanical properties. The glass‐fabric‐reinforced laminate prepared from one of the copolymer resins had a tensile streng