Henry's law constants of the solutes methane, nitrogen, oxygen and carbon dioxide in the solvent ethanol are predicted by molecular simulation. The molecular models for the solutes are taken from previous work. For the solvent ethanol, a new rigid anisotropic united atom molecular model based on Lennard-Jones and coulombic interactions is developed. It is adjusted to experimental pure component saturated liquid density and vapor pressure data. Henry's law constants are calculated by evaluating the infinite dilution residual chemical potentials of the solutes from 273 to 498 K with Widom's test particle insertion. The prediction of Henry's law constants without the use of binary experimental data on the basis of the Lorentz-Berthelot combining rule agree well with experimental data, deviations are 20%, except for carbon dioxide for which deviations of 70% are reached. Quantitative agreement is achieved by using the modified Lorentz-Berthelot combining rule which is adjusted to one experimental mixture data point. (c) 2005 Elsevier B.V. All rights reserved.