The mechanical alloying (MA) effect in σ -VFe intermetallic compound was studied by neutron and X-ray diffraction. The structure of MA σ -VFe powders were characterized by the X- ray diffraction with Cu- Kα radiation and neutron diffraction with monochromatic neutrons of 1.835\AA using a high resolution powder diffractometer (HRPD). Mechanical alloying of σ -VFe compound gives rise to a dramatic structural change. After 60 hours of MA, the Fe-Fe distribution of the σ - phase VFe tetragonal structure with 30 atoms in a unit cell is found to change into that of the σ -(V,Fe) solid solution with bcc structure, which is a stable phase at elevated temperature above 1200 ? C . A comparison of X-ray diffraction data for the α -phase has been also made with the corresponding neutron diffraction data. The (101) and (111) diffraction peaks of the σ -phase was clearly observed only in neutron diffraction pattern, which is believed to be a characteristic feature due to the chemical atomic ordering of σ - VFe phase.