N-1-Diamantylmaleimide was synthesized by reaction of maleic anhydride with 1-aminodiamantane, followed by dehydration with acetic anhydride and sodium acetate. Poly(N-adamantylmaleimide) (IIa) and poly(N-1-diamantylmaleimide) (IIb) were polymerized using 2,2’-azobisisobutyronitrile (AIBN) as an initiator under different experimental conditions such as various initiator concentrations, solvents, polymerization temperatures, and polymerization times. Polymerizations of N-1-adamantylmaleimide in benzene at 60 degrees C or in bulk gave polymers with molecular weights (2000-9500). The experimental results indicated that the propagation may be interrupted by steric hindrance of bulky and rigid substituents such as the adamantyl or diamantyl groups. In addition, the effect of chain transfer to monomer contributes to the relatively low activation energy. The glass transition temperatures of Ia and Ib were 204 and 216 degrees C, respectively. The temperatures at 5% weight loss of the polymers IIa and IIb were above 412 degrees C.