The benefits obtained from the addition of small quantities of chlorinated polyolefins to paving grade asphalt binders were investigated. A chlorinated polyethylene plastomer, Tyrin 2552, and a chlorinated olefinic elastomer, Tyrin CM0730, were added to asphalt binders at 3 and 5 wt % and subsequently reactively processed to facilitate compatibilization. The mixtures were analyzed for rheological performance relating to fatigue and rutting as well as low-temperature fracture performance. The addition of small quantities of these polymers to the asphalt binders resulted in significant improvements over conventional modifiers at both the high and low temperature extremes.