[en] A local, second-order (truncated) approximation is applied to the Hubbard model in three dimensions. Lowering the temperature, at half-filling, the paramagnetic ground state becomes unstable towards the formation of a commensurate spin-density-wave (SDW) state (antiferromagnetism) and sufficiently far away from half-filling towards the formation of incommensurate SDW states. The incommensurate-ordering wave vector does not deviate much from the commensurate one, which is in accordance with the experimental data for the SDW in chromium alloys. copyright 1997 The American Physical Society