tool to deal with uncertainties. In this paper, we introduce and study soft subrings and soft ideals of a ring by using Molodtsov's definition of the soft sets. Moreover, we introduce soft Soft set theory, proposed by Molodtsov, has been regarded as an effective mathematical subfields of a field and soft submodule of a left R-module. Some related properties about soft substructures of rings, fields and modules are investigated and illustrated by many examples. (C) 2010 Elsevier Ltd. All rights reserved.