Introduction: Cryopreservation of oocytes is a method of assisted fertilization by which cells are frozen at low temperatures in liquid nitrogen and stored until fertilization. Vitrification is a method of choice that carries less risk of oocyte damage during freezing and thawing. Indications for cryopreservation of oocytes can be medical, which includes women with malignant diseases and other health problems that reduce fertility, and social for the personal reasons of patients. Aim: The aim of the research was to determine the success of vitrification as a method of infertility treatment in its beginnings and to compare two legally regulated treatment periods. Methods and patients: The medical documentation of 128 secondary ICSI-ET cycles in patients treated at the Department of Human Reproduction of the University Hospital Center Rijeka was analyzed. The results are presented and compared based on a percentage calculation. Results: The proportion of patients younger than 34 years was 51%, on average 3-4 oocytes were thawed per treatment cycle. The proportion of interrupted cycles to the stage of fertilization was 38%, and the proportion of cycles with successful fertilization of oocytes was 55-70%. There was no tendency of lower fertilization success, nor worse development of the embryo towards the older reproductive age of the patients. Embryo transfer was done in 51% of secondary ICSI-ET cycles. The proportion of conceptions in the number of total treatment cycles started was 7%, and in the number of secondary cycles with embryo transfer 14%. Conclusion: Treatment success in the secondary ICSI-ET cycle is lower compared to natural monthly fecundability. The greatest risks of discontinuation of treatment are in the phase of freezing and heating of oocytes, ie at the time of fertilization. Since the results are different from other studies that indicate lower treatment success in elderly patients, our opinion is that the study needs to be continued due to the relatively small number of cycles analyzed in this study.