In vitro fertilization is a common method of fertilization in the case of both humans and animals. Although this method has developed very rapidly, there are still many unanswered questions about the optimal characteristics that oocytes should have for performing this procedure. The object of this study was to describe the correlation between the diameter and size of swine oocytes in relation to pubescence. The research was conducted on ovaries of piglets (n = 65) and adult swine (n = 69). Each oocyte was examined with and without the zona pellucida. The analysis showed that the average size of the oocyte from antral follicles is 134.59 ± 11.87 μm and the size of the oocyte is significantly larger for swine in the reproductive period than for piglets entering the prepubertal period. The differences were observed for oocytes both with and without the zona pellucida, as well as in the zona pellucida itself.