This paper presents an empirical approach for determining the effective lubricant rheological parameters in elastohydrodynamic contacts by using the experimental traction data taken from a conventional two-disc machine apparatus. These effective lubricant rheological parameters as functions of pressure and temperature are currently not available for most of the lubricants in practical applications, and are yet essential for traction calculations in elastohydrodynamic contacts. As a demonstration, comprehensive traction measurements are made with one gear lubricant for its effective rheological parameters. The lubricant parameters obtained are then incorporated into a traction model developed previously, and good agreement between model prediction and experimental observation is shown.