Let G be a graph with vertex set V and edge set E. Let d(i) be the degree of the vertex v(i) of G. The inverse degree, Randic index, and harmonic index of G are defined as I D = Sigma v(i)epsilon V-1/di, R = Sigma v(i)v(j) epsilon E 1/root d(i)d(j) , and H = Sigma v(i)v(j) epsilon E 2/(d(i) + d(j)), respectively. We obtain relations between ID and R as well as between ID and H. Moreover, we prove that in the case of trees, ID > R and ID > H.