A New Result about the Decidability of the Existential One-step Rewriting Theory Sebastien Limet and Pierre Rety Abstract: We give a decision procedure for the whole existential fragment of one-step rewriting first-order theory, in the case where rewrite systems are linear, non left-left-overlapping (i.e. without critical pairs), and non epsilon-left-right-overlapping (i.e. no left-hand-side overlaps on top with the right-hand-side of the same rewrite rule). The procedure is defined by means of tree-tuple synchronized grammars.