['Ovarian tissue cryopreservation is an emerging technique, also addressed to very young cancer patients, for whom it is not possible to perform an ovarian stimulation for oocytes freezing, before gonadotoxic treatment. In this cases, ovarian tissue must be cryopreserved for a long period of time and it is very important to know if it maintains fertility function after a long period of storage. Here we aimed to assess the effect of long-term storage on preservation and viability of cryopreserved human ovarian tissue.', 'Descriptive study of three cases of cancer patients whose cryopreserved ovarian tissue remained stored for 18\xa0years. Long-term stored tissue was examined by histological and immunohistochemical analysis, transmission electron microscopy, TUNEL assay and LIVE/DEAD viability/citotoxicity test.', 'Ovarian tissue stored for 18\xa0years showed a good morphology. Follicles presented negative staining for estrogen and progesterone receptors, positive staining for ki67 in granulosa cells and/or oocytes and for bcl2 in granulosa cells. Regarding stroma, patch/focal positive expression was found for estrogen receptor and ki67, diffusely positive expression for progesterone receptor and bcl2. After long-term storage, ultrastructural examination showed sub-cellular integrity of follicles and interstitial oedema foci. No apoptosis was observable by TUNEL assay. Stromal cell viability remained >97\xa0% during the culture period.'] Does long-term storage impact the quality of cryopreserved human ovarian tissue?