Purpose <p>Adolescents and young adults (AYA) who receive gonadotoxic treatment are at risk of future infertility. Fertility preservation is recommended to improve long-term quality of life, but outcomes are less well characterised in AYA than in adults. This study sought to analyse oocyte cryopreservation procedures, outcomes and ethical considerations, to improve counselling for AYA patients and their families.</p> Methods <p>Single-centre, retrospective observational cohort study of AYA patients (14–25 years) referred for fertility counselling and oocyte vitrification prior to gonadotoxic treatment between July 2018 and July 2025.</p> Results <p>Of 47 referrals received, 37 patients initiated ovarian stimulation, and 36 underwent oocyte cryopreservation. Oncological indications included haematological malignancy (43%), sarcoma (30%) and neurological (9%); benign conditions included aplastic anaemia (6%), neurofibromatosis (2%) and desmoid tumour (2%). The median age of patients who underwent ovarian stimulation was 16 years (range 13–24), with median AMH of 15 pmol/L (range 5.1–81.7 pmol/L). Ultrasound follicle tracking was performed transvaginally in 8/37 (21.6%) and transabdominally in 29/37 (78.4%); transvaginal oocyte collection was performed in 34/36 (94.4%) and laparoscopic in 2/36 (5.63%). Median number of oocytes cryopreserved was 11 (range 0–31), with oocyte maturity rate of 80.5% (range 50–100%).</p> Conclusions <p>Fertility preservation in post-pubertal AYA patients is feasible, and transabdominal ultrasound monitoring can be used successfully where transvaginal monitoring is not appropriate. Multidisciplinary input is important to ensure fertility preservation can be performed safely, particularly for those with haematological malignancies. To enable clinicians to appropriately counsel young patients, follow-up studies of livebirth outcomes will be important in the long term.</p>