Polish Epidian 5 two and 6 three (M = similar to390, similar to340, epoxy value 0.50, 0.54, resp.) epoxy resins were modified, 100 wt. pts., with resp. 5 and 10 wt. pts. bismaleimide (1,1'-(methylenedi-4,I -phenytene)bismateimide) at 130-140degreesC, cut out at 40degreesC with 20 wt. pts. of bisphenol A diglycidyl ether, cured with 35 wt. pts. 4,4'-diaminodiphenyimethane (100degreesC), allowed to harden 6 h at 60degreesC and reheated 1 h at 100, 120, 150 and 185degreesC. Nonmodified Epidians were hardened at 60degreesC and reheated 1 h at 100, 120 and 150degreesC. Martens deflection temperatures (123-140degreesC), glass transition temperatures (T 139-161degreesC, DSC), Charpy's impact strengths (10-31 kJ/m(2) ball hardness (121-152 MPa), and shear storage modulus (G), log damping decrement (lambda ) and mechanical loss tangent (tan 8) were determined. The bismaleimide-modified compositions had T-g higher by 15-20degreesC (max. 161degreesC for (10:100 w/w) bismaleimide-Epidian 6); higher hardness and lower impact strength, suggestive of higher crosslinking degrees; mechanical losses were evident only at ca. 160degreesC (vs. the 120degreesC).