MINDO/3 theoretical studies were carried out on sigmatropic hydrogen rearrangements in systems with central nitrogen atom; three systems studied being (1) N-methylformaldimine, (2) nitrous acid, and (3) formaldoxime-nitrosomethane systems. It was found that in system (1), 1,3-H shift is preferred whereas in systems (2) and (3), 1,2-H shifts are favored. The relative order of reactivity for the three systems was found to be (2) < (3) < (1), which is exactly the opposite to that found for the corresponding systems with central carbon atom.