Let p be a real number greater than one and let Γ be a graph of bounded degree. We investigate links between the p-harmonic boundary of Γ and the D p -massive subsets of Γ. In particular, if there are n pairwise disjoint D p -massive subsets of Γ, then the p-harmonic boundary of Γ consists of at least n elements. We show that the converse of this statement is also true.2010 Mathematics subject classification: primary 31C20; secondary 05C38, 31C45, 60J50.