Background/Objectives: Fertility preservation (FP) spans oncological and non‑oncological indications, including gonadotoxic therapies, benign haematological/metabolic disorders, conditions at risk of premature ovarian insufficiency, severe andrological disease, and elective plans to defer childbearing. We provide a sex‑integrated overview of established and emerging FP strategies and their real‑world effectiveness [1–10]. Methods: Narrative synthesis of guidelines and high‑quality studies (to 2025), prioritising ASCO/ESHRE guidance, systematic reviews, and multicentre/registry data covering oocyte/embryo cryopreservation, ovarian tissue cryopreservation (OTC), GnRH agonists, ovarian transposition, in vitro maturation (IVM), sperm banking, surgical sperm retrieval (SSR), testicular tissue cryopreservation (TTC), and spermatogonial stem‑cell (SSC) approaches [1–10]. Results: For women, oocyte vitrification is the first‑line option when time allows; OTC is established when stimulation is infeasible or in prepubertal girls, with endocrine recovery common and increasing pregnancy/live‑birth reports. For men, sperm cryopreservation before therapy is standard; SSR supports selected cases. Paediatric TTC is feasible but remains experimental, whereas paediatric OTC is clinically implemented. Random‑start COS and letrozole/tamoxifen protocols minimise treatment delay and hormonal exposure; GnRHa co‑treatment preserves ovarian function as an adjunct. Utilisation of banked gametes/tissue remains modest, underscoring the need for pathway optimisation [1–10]. Conclusions: FP should be embedded across oncology and non‑oncology pathways with timely referral, clear counselling on probabilities of live birth, and robust follow‑up. Standardisation, registry‑based evidence and long‑term offspring safety data are priorities to bridge the gap between laboratory potential and clinical effectiveness [1–10].

Background/Objectives: Fertility preservation (FP) has become an integral component of multidisciplinary care for patients at risk of treatment- or disease-related infertility. Although several established and emerging fertility preservation strategies are currently available, important challenges remain regarding patient selection, timing of intervention, long-term reproductive outcomes, and the translation of experimental approaches into routine clinical practice. This review critically appraises the current evidence on female and male fertility preservation, highlighting established techniques, emerging technologies, unresolved clinical challenges, and future research priorities. Oocyte vitrification remains the preferred strategy for postpubertal women when ovarian stimulation is feasible, whereas ovarian tissue cryopreservation has become an established option for selected patients requiring urgent treatment or for prepubertal girls. In men, sperm cryopreservation remains the standard of care, while fertility preservation in prepubertal boys is still investigational. Despite excellent laboratory outcomes, the real-world utilization of cryopreserved reproductive material remains unexpectedly low, highlighting persistent barriers in patient referral, counselling, and long-term follow-up. Methods: A structured narrative review was conducted using PubMed/MEDLINE and Embase to identify international guidelines, systematic reviews, meta-analyses, multicentre cohorts, registry-based studies, and original clinical investigations published between January 2015 and June 2025. Evidence was synthesized according to sex, age, fertility preservation indication, and clinical applicability. Interventions reviewed include oocyte and embryo cryopreservation, ovarian tissue cryopreservation (OTC), GnRH agonist co-treatment, ovarian transposition, in vitro maturation (IVM), sperm banking, surgical sperm retrieval (SSR), testicular tissue cryopreservation (TTC), and spermatogonial stem-cell (SSC) approaches. Results: Oocyte vitrification remains the preferred strategy for postpubertal women when ovarian stimulation is feasible, whereas ovarian tissue cryopreservation has become an established option for selected patients requiring urgent treatment or for prepubertal girls. In men, sperm cryopreservation prior to therapy is standard; SSR provides sperm for selected azoospermic cases. Paediatric FP strategies are asymmetric: OTC is clinically established, while TTC remains investigational. Random-start COS and aromatase inhibitor or tamoxifen protocols minimise treatment delay and hormonal exposure, and GnRHa co-treatment can serve as an adjunctive ovarian-protective measure. Despite high laboratory success, utilisation of banked gametes and tissue is modest, underscoring the need for structured referral pathways, patient counselling, and longitudinal follow-up. Conclusions: FP should be systematically integrated into both oncological and non-oncologic care pathways, with timely referral, age- and sex-specific counselling on live-birth probabilities, and long-term follow-up. Future priorities include harmonization of clinical protocols, standardized outcome reporting, registry-based long-term follow-up, and validation of emerging technologies to improve both reproductive outcomes and equitable access to fertility preservation.