We have investigated perfection of atomic rows on iron-based Heusler alloy films on Ge(111) planes by using ion channeling technique in order to find the dominant factors for the perfection. Fe3Si/Ge(111) and Fe2CoSi/Ge(111) have a high quality of atomic rows at the heterointerface like that of perfect crystals. Fe3-xMnxSi/Ge(111) (x=0.84, 0.72 and 0.36) interfaces have imperfection of atomic rows which may be controlled by both the lattice mismatch with the Ge substrate and the Mn-Si pairs due to the site disorder in the film with the Mn content x>0.75. Analysis of axial channeling parameters employed in this study is very useful for quantitative evaluation of perfection of atomic rows at the heterointerface. (C) 2011 Elsevier B. V. All rights reserved.