Neutron diffraction performed on Nd 6Fe 13− x Al 1+ x ( x=1–3) and La 6Fe 11Al 3 powder samples has shown a selective distribution of the Al atoms among the five non-rare-earth positions filling up successively the 4a Si and the 16l 2 Fe4 sites of the prototype Nd 6Fe 13Si structure with increasing x. Traces of Al could be detected at the 16k Fe site when x=3. The magnetic ordering is associated in all cases with the wave vector q =(0 0 1) ( I p magnetic lattice with anticentering translation). All Nd compounds display almost easy axis behaviour below T N and spin reorientation transitions at lower temperatures from easy axis to easy cone. A full set of neutron data in the entire magnetically ordered regime has been analysed to derive the exact magnetic structural parameters and possible spin reorientation transitions. The largest ordered moment values were observed for Nd 6Fe 12Al 2 at 1.5 K (3.2(2) μ B/Nd atom, close to the free ion value, and 2.1 μ B/Fe atom) while no detectable moment value could be found for the Fe4 site for higher Al concentrations. The iron moment values are in satisfactory agreement with Mössbauer and magnetization results.