© 2022 Elsevier B.V.Objective: Oocyte donation (OD) cycles have been used extensively over the last decades due to high success regarding live birth rate (LBR). We evaluated the reproductive outcomes of fresh and vitrified sibling oocytes in terms of fertilization rates, blast ratio, clinical pregnancy rates, and LBR. Materials and methods: This retrospective cohort study was conducted at a tertiary in vitro fertilization (IVF) center. A total of 7515 metaphase II (MII) donor oocytes from 304 donor cycles for 609 oocyte recipients undergoing embryo transfers with either fresh or cryopreserved-thawed donor oocytes. Donor cycles that provided both 12 fresh MII oocytes to be used for one recipient and at least 12 MII oocytes which were suitable for vitrification to be used for another recipient at another time were analyzed. Fertilization rates, blastocyst ratios, clinical pregnancy rates (CPR), LBR were evaluated as main outcome measures. Results: When the fresh and cryopreserved-thawed OD cycles were compared, there was no significant differences between two groups in terms of age of the recipient (41.9 ± 5.7 and 40.3 ± 6.8, p = NS), number of MII oocytes (12.1 ± 0.3 and 12.6 ± 0.8, p = NS), number of 2 pronuclear (PN) (9.1 ± 1.6 and 9.7 ± 2.0, p = NS), blastocyst ratio (58.9 ± 21.7 and 51.3 ± 21.2, p = NS) and number of transferred embryos (1.9 ± 0.3 and 1.9 ± 0.3, p = NS). There was no significant difference between fresh and cryopreserved-thawed sibling donor oocyte cycles in terms of CPR (66.8 % and 60.7 % respectively, p = NS) or LBR (59.5 % and 55.1 %, respectively; p = NS). Miscarriage and multiple gestation rates were similar between groups (p = NS). Log-binomial regression analysis revealed that the use of fresh sibling oocytes was not associated with CPR or LBR, when compared to cryopreserved-thawed oocytes. Conclusions: There was no significant difference in terms of reproductive outcomes between sibling fresh OD and cryopreserved-thawed OD cycles.