Osteoporosis and fractures are common after heart and lung transplantation and often progress despite antiresorptive treatment (1). Anabolic agents such as romosozumab stimulate bone formation and may provide greater gains in bone mineral density (BMD) than antiresorptive therapy (2, 3), but evidence in transplant recipients is limited (4, 5). We aimed to describe BMD and fracture outcomes in heart and lung transplant recipients with severe osteoporosis treated with romosozumab. We performed a retrospective single-centre review of 23 recipients treated with romosozumab 210 mg monthly for 12 months. Lumbar spine and total femur BMD were compared before treatment and at 12 months in the 16 patients with paired dual-energy X-ray absorptiometry scans, and fractures and deaths were recorded. Median age was 63 years, 70% were female, and the cohort comprised 8 heart and 15 lung recipients a median of 4 years after transplantation; 83% were receiving prednisolone (median 5 mg/day) and 96% had a prior fracture. In all but one patient, BMD stabilised or increased at both sites. The median change was +8% (range -12 to +38) at the spine and +5% (range -2 to +23) at the total femur. The single patient who lost BMD at both sites had received three years of zoledronate then four years of denosumab, with a missed denosumab dose before commencing romosozumab. Six of 22 followed patients (27%) sustained a fracture and four (17%) died, none from myocardial infarction or stroke. In this, the largest series to date, romosozumab was associated with stabilisation or improvement in lumbar spine and total femur BMD in heart and lung transplant recipients, although fractures continued to occur. Larger controlled studies are required.