Habibi, A., Hosseini, A., Farrokhi, N., Amidi, F., Carvalhais, I., Chaveiro, A. and Moreira da Silva, F. 2011. Short Communication: Successful vitrification of mouse oocytes using the cryotop method with moderate cryoprotectant concentrations. Can. J. Anim. Sci. 91: 385-388. The response of vitrified mouse M_II oocytes in the presence of two concentrations of cryoprotectants [vit₁ (15%: 7.5% dimethyl sulfoxide (DMSO) 7.5% ethylene glycol (EG) and vit₂ (30%: 15% DMSO 15% EG)] was analyzed to investigate whether reducing cryoprotectant concentrations can affect oocyte survival after cryopreservation by the cryotop method. After thawing the survival, fertilization, cleavage and blastocyst rates were compared with unfrozen oocytes. It can be concluded that 15% cryoprotectant (7.5% DMSO 7.5% EG), instead of the commonly used 30% (15% DMSO 15% EG), could be helpful by moderating the probable toxic effects of vitrification solution in mouse oocyte during vitrification by cryotop.