We investigated the microstructure and mechanical strength of Ag-added DyBa2Cu3Oy (Dy123) bulk superconductors with various Dy2BaCuO5 (Dy211) contents. Single-grain Dy123 bulk samples 32 min in diameter with the addition of 5-40 mol% of Dy211 and 10 wt.% of Ag2O were fabricated in air. The sample with 5 mol% Dy211 contained many macro-cracks in the ab-plane. The amount of cracks decreased with increasing Dy211 content. Three-point bending tests were performed at room temperature to measure the mechanical properties. The average bending strength of the sample with 5 mol% Dy211 was 73 MPa. The strength was improved to 95 MPa with an addition of 40 mol% Dy211. (C) 2004 Elsevier B.V. All rights reserved.