Abstract： Objective To compare the effects of two vitrified frozen-thrawed procedures on spindle and chromosome configurations of mature (M Ⅱ ) human oocytes. Methods M Ⅱ oocytes which failed fertilization during in vitro fertilization and embryo transfer (IVF-ET) were collected and treated with either procedure A (cryopreservation agent with FBS formula gradient balancing,A group) or procedure B (cryopreservation agent with recombined serum albumin B group). The same procedures were given to a group of un-cryopreserved oocytes (control group). After thawing,surviving oocytes of study groups and fresh oocytes of control group were stained by immunofluorescence. Then the spindles and chromosomes of oocytes were observed under confocal laser scanning microscope. Results The survival rates of group A and B were 95.8% (23/24) and 96.7% (29/30) respectively,with no significant difference betw een the study groups (P>0.05).13% (3/23) of spindle and 13% (3/23) of chromosome configurations in the A group remained normal,comparable with the findings in control group[18.2%(6/33) and 18.2%(6/33),respectively](P>0.05),while normal rates of spindle and chromosome configurations in B group[0%(0/29) and 0%(0/29)]were significantly lower than those in control group (P<0.05). The rates with absent spindle in A group and control group were 65.3% (15/23) and 39.4% (13/33) respectively (P>0.05),while the rate with absent spindle in B group was 79.3% (23/29),with significant difference as compared with control group (P <0.01 ). Conclusion The vitrified frozen-thrawed procedure A is less harmful to the spindle and chromosome configurations of human M Ⅱ oocytes.