The vapor pressure of liquid argon, krypton, and xenon was measured from below the normal boiling temperature to close to the critical temperature. Functional relations were fitted by a multiple regression analysis to the experimental data. Data of other authors are compared directly with the results presented here.Comparison of the vapor pressure curves for the three liquids showed that the classical corresponding states principle was obeyed only poorly and that it was necessary to include quantum corrections in comparing the reduced curves. The adjusted reduction factors agreed reasonably well with those found from vapor pressure analysis by other workers. De Boer plots on the basis of our potential parameters are more linear than those using the parameters of Boato and Casanova.