Abstract Introduction With government and NHS drivers, there has been an increase in menopause awareness and management. The NHS Business Services Authority reported a 29% increase in hormone replacement therapy (HRT) prescribing between 2022-2023, with expectation that this would rise further with introduction of the new HRT prepayment certificate in April 20231. Partly due to celebrity sway and supported by national guidance2,3 there is patient expectation towards transdermal oestrogen with natural progesterone HRT. Older women, some years since undergoing natural menopause, are also seeking advice on HRT use (3) with referrals accepted by specialist menopause clinics. Aims This service evaluation project was undertaken to evaluate the prescribing of HRT regimens in complex patient cases seen within a specialist menopause clinic and included assessment of those advised to use natural progesterone as part of their HRT regimen, for endometrial protection2,3. Method 366 specialist menopause clinic appointments over 6 months (05.01.23-22.06.23) were retrospectively evaluated, with patients seen by a multidisciplinary team within an outpatient secondary care setting. Exclusion criteria included appointments not attended, those that were incorrectly booked or patients with inaccessible records. Data was collected using electronic patient records with results analysed using Microsoft Excel. Results Of 327 (89%) appointments evaluated, the patient age ranged between 30-84 years (median age 53). HRT was recommended for 288 (88%) patients. HRT was not recommended in cases such as antiphospholipid syndrome, breast cancer without genitourinary symptoms, in those of advanced age or in line with patient choice with patient decision not to take HRT after an individualised risk benefit evaluation. For 26 (9%) patients, only topical oestrogen treatment for localised genitourinary syndrome symptoms was advised. 171 (52%) patients were postmenopausal, 61 (19%) perimenopausal, 46 (14%) with premature ovarian insufficiency and 20 (6%) with surgical menopause. For 22 patients (7%) with Mirena intra-uterine system in situ, their menopause phase could not be accurately defined. 243 (88%) of those recommended HRT were advised a combined regime; 154 (53%) continuous combined; 67 (23%) sequential combined and 22 (9%) oestrogen with Mirena coil. For patients accepting combined HRT, one third (81) were recommended natural progesterone, with the other patients using progestogens for endometrial protection. Of these 81 patients, 77 (95%) were recommended transdermal oestrogen in combination with natural progesterone. For patients recommended natural progesterone, 68 (84%) were for doses in line with licensing and current British Menopause Society guidance. For 10 patients the off-label recommendation involved doubled doses of natural progesterone to help with control of unfavourable bleeding. Discussion For prescribing of natural progesterone, we assumed that our recommendations to the GP were enacted. With retrospective evaluation of patient letters as a limitation, this project identified that within our specialist clinic complex patient population, a recommendation for natural progesterone was made for one third of patients suitable for combined HRT use. When not prescribed in line with licensing, this was due to issues with vaginal bleeding. Acknowledgments Biranavi Kirupakaran, Sahil Misri, Hernani Almeida, Medical Students, Imperial College London for data collection.