Let G = (V,E), V = {v1, v2, . . . , vn}, be a simple graph without isolated vertices, with the sequence of vertex degrees d1 ≥ d2 ≥ · · · ≥ dn > 0, di = d(vi). If vertices vi and v j are adjacent in G, we write i ∼ j, otherwise we write i / j. The inverse degree topological index of G is defined to be ID(G) = ∑n i=1 1 di = ∑ i∼ j ( 1 d2i + 1 d2j ) , and the inverse degree coindex ID(G) = ∑ i/ j ( 1 d2i + 1 d2j ) . We obtain a number of inequalities which determine bounds for the ID(G) and ID(G) when G is a tree.