A two-part polyurethane adhesive comprising a prepolymer having the reaction product of a non-ionic surfactant and an allophanate modified isocyanate and a curative having a urethane modified high molecular weight polyol, a urethane modified cross-linking compound and a non-urethane modified low molecular weight chain extending compound. The curative has less than 5 equivalent percent total amino and hydroxyl groups having an equivalent weight greater than about 200. The two-part polyurethane adhesive may be used to adhere one or more substrates and can generally be applied without primer or any significant surface preparation.