DyMn2O5 multiferroic nanorods with radial (D) x axial (<L-C>) lengths of 24(9) nm x 46(12) nm, 36(9) nm x 84(26) nm and 111(22) nm x 212(84) nm, were fabricated through the hydrothermal method. The aspect ratio <L-C> /D of the nanorods retained the value 2 at different annealing temperatures (T-a = 400, 800, and 1000 degrees C for <L-C> = 46, 84, and 212 nm, respectively). Antiferromagnetic magnetic ordering started at approximately 42 K, 42 K, and 50 K for <L-C> = 46 nm, 84 nm, and 212 nm samples, respectively. The saturation magnetic moment (<mu(z)>(s)), Hc, and Mr decreased as <L-C> increased. The results of magnetic hysteresis experiment implied that magnetic domain sizes decreased as the <L-C> increased. The size effect not only merges the nanorods into larger crystals but also reduces interior magnetic domain sizes. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).