The effect of a modifying additive (brown-coal pyrolysis tar) on the asphalt oxidation process has been investigated. The dependences of the softening temperature and the dynamic viscosity of the product asphalts upon the duration of oxidation and the amount of the additive have been determined, and the oxidation rate constants and the viscous-flow activation energies have been calculated for the oxidized asphalts. On the basis of experimental data, it has been shown that the introduction of the modifying additive into vacuum residue leads to a decrease in dynamic viscosity and softening temperature of the blown asphalts owing to its inhibitory effect on the oxidation process. Asphalts derived from the modified feedstock are characterized by a more ordered structural organization compared with those obtained from the unmodified feedstock.