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RESEARCH-QUESTION What is the clinical usefulness of oocyte cryopreservation for fertility preservation in women with ovarian endometriosis? DESIGN Clinical characteristics were retrospectively analysed in 34 women with endometrioma before a planned ovarian cystectomy. Ovarian stimulation outcomes were compared according to laterality. A one-to-one propensity score-matched analysis was conducted to compare ovarian stimulation outcomes of the first cycle in patients with endometrioma undergoing fertility preservation with those in infertile patients without endometrioma who underwent IVF treatment. The number of oocytes cryopreserved in repeated ovarian stimulation cycles was analysed. RESULTS The mean endometrioma size at diagnosis was 6.0 ± 2.5 cm. The mean age, serum anti-Mullerian hormone levels and number of oocytes cryopreserved were 30.7 ± 5.9 years, 1.85 ± 1.14 ng/ml, and 4.8 ± 3.2, respectively. The number of oocytes cryopreserved in bilateral endometrioma compared with unilateral endometrioma patients was 4.1 ± 2.9 versus 5.7 ± 3.4 (P = 0.600). In the propensity score-matched cohort (n = 22 per group), the number of oocytes retrieved was significantly lower in the patients with endometrioma undergoing fertility preservation compared with that in infertile patients without endometrioma (5.4 ± 3.8 versus 8.1 ± 4.8; P = 0.045). A total of 13 (38.2%) patients with endometrioma underwent repeated stimulation. The median (interquartile range) number of cryopreserved oocytes at the first and the second cycle were 3.0 (2.5-6.0) and 5.0 (2.5-7.5), respectively. CONCLUSIONS Women with endometrioma should be counselled about oocyte cryopreservation for fertility preservation before surgery. The number of cryopreserved oocytes can be increased by repeated oocyte retrieval.