Background: Severe developmental disability increases the risk of osteoporosis¹ . Predictors of fracture are poorly-defined in this group. Methods: We performed an audit of patients with moderate/severe developmental disability attending an outpatient endocrine clinic from 2010-2013. Demographic data, mobility, medication use, secondary screening,  prior fractures, BMD and osteoporosis therapies were retrospectively obtained from records. Results: 47 patients, average age 48±6 years were reviewed.  64% male, 96%  in long-term residential-care. 55% ambulant without assistance, 28% wheelchair bound. Comorbidities included hypothyroidism (38%), reflux (64%) and seizure disorders (66%). 31 patients took anticonvulsant medication. Of 28 patients with known fractures, distal peripheral fractures were the most common site of first fracture (46%), followed by vertebral (32%) and proximal peripheral (21%). In 14 cases, a traumatic episode was not identified - 10 discovered on x-ray (mostly vertebral) and 4 found after carers noted swelling/deformity. 15(54%) had a subsequent fracture and 11% had multiple subsequent fractures. 7 re-fractures occurred whilst on current oral bisphosphonate therapy, another 2 occurred in patients with previous oral bisphosphonate use, remaining 6 had  received no anti-resorptive treatment. 4 patients switched to zoledronate due to falling BMD and concerns about tolerance or absorption of oral bisphosphonates. Difficulties due to scoliosis/kyphoscoliosis/deformity were noted during BMD measurement in 23 of 46 patients. The mean(±SD) lumbar-spine T-score was -2.0±1.3, and femoral-neck T-score was -3.1(±1.0), with no difference between those who did or did not fracture. Predominantly-ambulant patients were significantly more likely to have sustained fractures than predominantly-wheel-chair bound (78% vs 35% p=0.003). There was no significant difference in fracture site or BMD T-scores between ambulant and non-ambulant patients. Anticonvulsant use did not associate with fracture or BMD in this small sample. Conclusion: Distal peripheral fractures and 'asymptomatic' vertebral fractures found on x-ray are common in this population, even in the wheelchair-bound. Greater mobility was associated with greater fracture risk. Re-fracture rate is significant, despite oral bisphosphonate therapy. Difficulties with BMD assessment,  gastro-intestinal problems and under-recognition of fractures are potential issues. Scant evidence is available to guide management decisions such as screening, fracture-risk prediction and optimum use of osteoporosis therapy in this relatively young cohort.