Abstract.We have investigated the magnetic ground state of the antiferromagnetic Kondolattice compounds CeMAl 4 Si 2 (M = Rh, Ir) using neutron powder diffraction. Although both of these compounds show two magnetic transitions T N 1 and T N 2 in the bulk properties measurements, evidence for magnetic long-range order was only found below the lower transition T N 2 . Analysis of the diffraction profiles reveals a commensurate antiferromagnetic structure with a propagation vector k= (0, 0, 1/2). The magnetic moment in the ordered state of CeRhAl 4 Si 2 and CeIrAl 4 Si 2 were determined to be 1.14(2) and 1.41(3) µ B /Ce, respectively, and are parallel to the crystallographic c-axis in agreement with magnetic susceptibility measurements.