This paper deals with the influences of phenol formaldehyde resin on the rheological properties of petroleum bitumen. Different amounts of phenol formaldehyde were doped into the bitumen of 50/70 penetration grade and variations in viscosity as a function of temperature and additive concentration were determined. The effects of the phenol formaldehyde additive were examined by conventional and Superpave test methods. Adhesion and stability of bitumen aggregate mixtures prepared using pure and modified bitumen were compared using Nicholson stripping and Marshall tests. The appropriate dosage of the additive yielding the best rheological and performance properties in hot climates was found to be 2% (w/w). Appreciable decreases in the formation of rutting, bleeding, stripping, and cracking in bitumen may be obtained through phenol formaldehyde addition. (C) 2014 American Society of Civil Engineers.