This research aims to compare morphological changes and HSP70 expression of fresh oocytes and vitrified oocytes. Of the fresh oocytes and vitrified oocytes, it was observed the cytoplasmic changes and expression of HSP70. The oocytes were vitrified using hemistraw into containers containing liquid nitrogen at -196° C. Expression of HSP70 in fresh oocytes and vitrified oocytes was analyzed by immunocytochemical method. This research analyzed the changes in cytoplasm and HSP70 expression in oocytes in two treatment groups. Treatment group 1 was the treatment of fresh oocytes without vitrification, and group 2 was the treatment of vitrified oocytes post warming. In each treatment group, it was analyzed changes in cytoplasm and HSP70 expression in fresh oocytes and vitrified oocytes. Of the results in this research, there was cytoplasmic degeneration affecting the viability of vitrified oocytes post warming. This research showed that the percentage of vitrified oocyte viability was 50%. The results of analysis of immunocytochemical data showed that there was an effect of post warming vitrification on oocyte HSP70 expression. These results indicate that the post warming vitrification of oocytes causes a decrease in viability and increase in HSP70 expression.