A practical means of overcoming the limitation in accuracy of conformational analysis due to incompleteness of basis sets used in ab initio calculations involves calculating the energy with a series of systematically improving basis sets and extrapolating to the basis set limit. We report here a focal-point conformational analysis for methanol. The Hartree-Fock energy converges exponentially to the basis set limit, while the convergence of second-order correlation energy is well described by the formula EcorX = Ecorinfty + A3 X-3 + A5 X-5. This formula also describes well the convergence of fourth-order correlation energy. The height of the rotational barrier at the Hartree-Fock level can be obtained reliably by taking the difference of the extrapolated energies of the two conformations and correcting the difference for correlation effects. Electron correlation has only a small decreasing effect on the height of the rotational barrier in methanol. The focal-point value for the torsional barrier in methanol is 0.999±0.007 kcal/mol.