A few years back T. Vértesi et al. (J Phys Chem A 2005, 109, 3476) gave an elegant procedure to derive the adiabatic-to-diabatic transformation angle (ADT-angle) for lowest two states, γ 12, in presence of their interaction with the higher states. In this article, we explicitly solved the coupled differential equations involving the ADT-angles describing the mixing of four interacting states for the first time to get all the ADT-angles, γ ij's (including the γ 12) associated with well-defined topological phases. In application to a suitable configuration space (CS) of a molecular system, we have demonstrated well-defined Berry phases (Berry M. V., R Soc London Ser A 1984, 45, 392) for an isolated system with as many as four strongly interacting states. © 2012 Wiley Periodicals, Inc. Copyright © 2011 Wiley Periodicals, Inc.