AbstractThe upper critical magnetic field for a monocrystalline superconductor with cubic symmetry is calculated using the Method of the Correlation Function. The symmetry of the system leads to an eigenvalue equation which is solved with perturbation-theoretic methods. The upper critical field is calculated for dirty superconductors in the lowest order for which anisotropy is present. For clean superconductors, a higher order is calculated. Some results are critically compared with those in a paper by HOHENBERG and WERTHAMER.