Pr-substituted (Dy1-xPrx)BaSrCu3O7-delta (x = 0.0, 0.1, 0.2, 0.4 and 0.7) has been investigated for its superconducting and elastic properties. Structural transition from orthorhombic to tetragonal symmetry is observed at x = 0.1. Temperature-dependent sound velocity was measured using the pulse-echo overlap method. Elastic anomalies in the form of lattice stiffening with decreasing temperature were observed above 200 K. These anomalies were attributed to oxygen vacancy orderings in the Cu(1)O plane and also depended on the configurational state of oxygen orderings which is strongly influenced by Pr-doping. (C) 2003 Elsevier B.V. All rights reserved.