Summary Background Paediatric patients with recessive dystrophic epidermolysis bullosa (RDEB) are at risk of vitamin D deficiency, owing to lack of sunlight from reduced mobility and having large areas of skin being covered with dressings, and to impaired nutritional intake and status. Aim To establish an appropriate level of vitamin D supplementation in paediatric patients with RDEB. Methods Patients with RDEB attending the EB tertiary multidisciplinary team clinic were enrolled. Serum levels of total 25(OH)D were retrospectively recorded for the study period 2012–2018. Data from clinical records on supplements, bone mineral density (BMD) Z scores, compliance, and use of enteral feeds and/or formula were also recorded. Results In total, 24 patients met the inclusion criteria: 20 with severe RDEB, 3 with RDEB inversa and 1 with intermediate RDEB. Of the 24 patients, 21 (88%) were advised to take a vitamin D3 supplement in line with Department of Health Guidelines (UK), with the remaining 3 patients receiving sufficient intake from formula or enteral feeds. Thirteen of the 24 (54%) had vitamin D deficiency or insufficiency despite advice to supplement; 9 of these 13 (69%) subsequently started or increased the dosage of vitamin D supplements and levels became sufficient (> 50 nmol/L), while the remaining 4 patients (31%) continued to have persistent insufficient levels due to noncompliance with supplements. Reasons for noncompliance were palatability, cost and forgetting to take the tablets. The dose required to maintain sufficient serum levels increased with age, up to 300% of the reference nutrient intake (RNI). Conclusion All patients with RDEB require a supplement or a formula or enteral/sip feed containing vitamin D to maintain sufficient serum vitamin D. The dose required increases with age and can be up to three times higher than the RNI for the normal population. Compliance may improve using a once‐weekly loading dose of vitamin D3. Vitamin D deficiency was not solely causative of a low BMD Z score.