Measurements are reported for the dynamic viscosity of four binary alkanol + alkane mixtures of ethanol and 1-propanol with hexane and heptane. The measurements were conducted at 298.15 K and in a pressure range from atmospheric to 520 bar. A self-centering falling body viscometer was used for the measurements. All four systems exhibit negative viscosity deviations over the full composition and pressure ranges. The experimental data are discussed in terms of the specific interactions involved in the systems.