The objective was to develop a simpler, more reliable vitrification method for porcine embryos. Prepubertal donor gilts were induced to ovulate with eCG and hCG, and then inseminated artificially. Morulae and expanding blastocysts approximately 200 mu m in diameter were collected 6 or 7 d after hCG treatment. Embryos collected from donor gilts were maintained, so as to be individually recognizable, and handled in batches of four or five. The embryos together with a minimum volume (<2 mu L) of vitrification solution were placed onto stainless steel metal meshes or plastic plates, and then plunged into liquid nitrogen-metal mesh vitrification (MMV) and plastic plate vitrification (PPV), respectively. The meshes or plates were stored in 1.8-mL cryotubes submerged in liquid nitrogen. Stored embryos were subsequently removed, Cultured in medium for 24 h, and then assessed for viability. The survival rate (84.4%) of expanding blastocysts cooled by MMNI was higher than that (53.1 %) of embryos cooled by PPV (P < 0.05). There was no significant difference in total cell number between MMV and PPV. The survival rate of morulae cooled by MMV was 55.0%. Transfer of 200 expanding blastocysts cooled by MMV to 10 synchronized recipient gilts resulted in 37 live piglets from 7 recipients. In conclusion, the MMV method was ail effective vitrification procedure for cryopreservation of expanding porcine blastocysts. However, there was a batch effect on embryo survival after vitrification. (c) 2008 Elsevier Inc. All rights reserved.