Let G be a connected graph, and let ?b(G) and SQ(G) be the edge bipartiteness and the signless Laplacian spread of G, respectively. We establish some important relationships between ?b(G) and SQ(G), and prove SQ(G)?2 (1+cos?/n) with equality if and only if G = Pn or G = Cn in case of odd n. In addition, we show that if G?Pn or G?C2k+1; then SQ(G)?4; with equality if and only if G is one of the following graphs: K1,3, K4, two triangles connected by an edge, and Cn for even n. As a consequence, we prove a conjecture of Cvetkovic, Rowlinson and Simic on minimal signless Laplacian spread [Eigenvalue bounds for the signless Laplacian, Publ. Inst. Math. (Beograd), 81(95)(2007), 11-27].