OBJECTIVES: Intellectual disability (ID) and epilepsy are independent risk factors for osteoporosis. Diverse predisposing factors influence this, for example in ID, genetics and poor nutrition and in epilepsy, anti-seizure medication (ASM). Around 25% people with ID have epilepsy, majority treatment resistant. ASMs polypharmacy is common. However, little is known about the bone-related characteristics of this vulnerable group. A prospective observational cohort study of bone profile across a community ID Epilepsy service was undertaken to understand this. MATERIALS & METHODS: Participants were on minimum 2 years of ASMs. Baseline demographics, epilepsy data, bone metabolism biomarkers, bone mineral density (BMD) and vitamin D levels were collected. Doses needed to correct vitamin D insufficiency/deficiency were calculated. RESULTS: At baseline, of 104 participants, 92 (90.2%) were vitamin D insufficient/deficient. Seventy-six (73.1%) had a DEXA scan, 50 of whom-in the osteopaenic/osteoporotic range. DEXA scores between ambulant and non-ambulant patients were significantly different (p = .05) but not for ID severity. A high alkaline phosphatase (ALP) predicted lower vitamin D levels. Borderline significance (p = .06) in calcium levels between normal and high ALP was identified. There were no significant associations between parathyroid hormone, inorganic phosphate and magnesium levels, with vitamin D status or DEXA hip T-scores. Normalizing vitamin D levels (mean 101.4 nmol/L) required an average of 1951IU cholecalciferol daily. CONCLUSIONS: Vitamin D deficiency is highly prevalent in people with ID and epilepsy treated with ASMs impacting likely on their bone health. Screening with vitamin D levels, ALP and DEXA in this group should be pro-actively and routinely considered.