Influence of defects in body-centered cubic (bcc) iron on its radiation damage character has been studied by numerical integration of equations of motion of a large set of atoms on a high-speed computer. Characteristically, the following defects were chosen: vacancy, <100> and <110> split interstitials, and interstitial carbon atoms in an octahedral position. The threshold energy for displacing a carbon atom is found to be highly dependent on the direction of the knock on which is similar to the case of iron atoms. The lowest threshold energy is found to be less than 3 eV in the <100> direction and the highest in <110> direction. Channeling of carbon atoms was observed only in <100> direction. Defects can also influence the dynamics of processes of radiation damage, namely, collision chains. Vacancies strongly affect collision chains in <100> and <111> directions which result in defocusation. Split interstitials, if not parallel to collision chain, almost instantly stop propagation. The largest effect is produced by interstitial carbon atoms; they rapidly slow down all types of collision chains.