Polymerase chain reaction-restriction fragment length polymorphism) was performed on the cistron of rDNA in the two groups of infective larvae Trichostrongylus colubriformis—the population with and without ability to undergo arrested development. General primers designed by Caenorhabditis elegans rDNA were used for the amplification of the rDNA cistron between genes 18S and 28S. Amplified fragments were digested by using a series of restriction endonucleases. Hinc II restriction profiles unique for each T. colubriformis populations were observed, and therefore enzyme Hinc II appears to be useful for the determination of populations with and without the ability to undergo arrested development. Molecular markers of arrested development ability have not been studied on this part of rDNA before.