The Barus equation relating viscosity to pressure includes a pressure-viscosity coefficient used widely by investigators even though that coefficient is grossly inaccurate at elevated pressures. A new empirical equation was developed relating viscosity to pressure. The equation is mathematically simple and provides two coefficients that are satisfactory over a wide pressure range. These coefficients are temperature dependent and produce a pressure-viscosity relationship with a maximum error of only about 8 percent at a temperature of 37.8°C over a pressure range to 0.60 GPa for a number of fluids.