A simple method for the prediction of vapor pressures of pure compounds from knowledge of the normal boiling point temperature is presented. Typical errors down to 10(-5) bar (1 Pa) are below 20% and are off only by a factor of 2-3 down to 10(-9) bar (10(-4) Pa), which must be considered very satisfactory considering the simplicity of the method and the uncertainty in the very low vapor pressure data. For higher pressures. up to 5 bar, very satisfactory results are obtained with typical errors below 3% but somewhat higher for alcohols.