A neutron-diffraction study of a single crystal of DySb has shown that at about 9.5 K the compound has a crystallographic as well as a magnetic transition. Below the transition DySb is monoclinic (almost tetragonal) with type-II antiferromagnetic ordering. The direction of the magnetic moment is close to the tetragonal axis at low temperature and tilts away with increasing temperature. The extrapolated saturation moment is (9.8±0.2)μBdysprosium atom. © 1973 The American Physical Society.