Polymaleamides from bisisomaleimides and diamines have been prepared by ring-opening polyaddition. These polymaleamides were found to have inherent viscosity in the range 0.30-0.42 g dl(-1). The identities of the polymaleamides were confirmed by elemental analysis, and i.r., u.v.-visible and H-1 n.m.r. spectoscopies. The thermal degradation behaviour of the polymaleamides was studied by mass spectrometry and thermogravimetric analysis; fragmentation schemes for the polymaleamides are proposed.