The Dzyaloshinskii-Moriya (DM) interaction is induced by the spin-orbit interaction with an antisymmetric component in the exchange coupling. We have examined a possibility to detect the DM interaction as well as the non-secular part of the dipolar interaction for weakly-coupled systems by analyzing relaxation processes from the double to single quantum coherence by pulsed EPR measurement. Numerical simulation for two and three spin-1/2 systems indicates that the proposed measurement has a capability to determine the signs of the DM interactions that are important to distinguish spins in a uniform field from in a staggered field. (C) 2008 Elsevier B.V. All rights reserved.