AbstractNew monomers with a high content of halogens,N‐(pentachlorophenyl) maleimide (1) andN‐(2,4,6‐tribromophenyl) maleimide (2) were prepared. The products of their radical polymerization consist of oligomers. Of these, products with the degree of oligomerization, n, ranging from 1–4 and from 1 to 3 were separated on a gel chromatograph for1and2, respectively. Their structures were determined from the mass spectra. The elution volumesVnof the individual oligomers were found to be a linear function of logMn. The radical polymerization mechanism of1and2is discussed on the basis of the character of ol