BackgroundThe aim of this study is to evaluate vitamin D levels in children with latent and active TB compared to healthy controls of the same age and ethnical background.MethodsA multicenter observational study has been conducted in three tertiary care paediatric centres: Anna Meyer Children's University Hospital, Florence, Italy; Evelina London Children's Hospital, London, United Kingdom and Great Ormond Street Hospital, London, United Kingdom. Vitamin D was considered deficient if the serum level was <25 nmol/L, insufficient between 25 and 50 nmol/L and sufficient for a level >50 nmol/L.ResultsThe study population included 996 children screened for TB, which have been tested for vitamin D. Forty-four children (4.4%) had active TB, 138 (13.9%) latent TB and 814 (81.7%) were controls. Our study confirmed a high prevalence of hypovitaminosis D in the study population. A multivariate analysis confirmed an increased risk of hypovitaminosis D in children with latent and active TB compared to controls [(P = 0.018; RR = 1.61; 95% CI: 1.086-2.388), (P < 0.0001; RR = 4.587; 95% CI:1.190-9.608)].ConclusionsHypovitaminosis D was significantly associated with TB infection in our study. Further studies are needed to evaluate a possible role of vitamin D in the treatment and prevention of tuberculosis in children.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0652-7) contains supplementary material, which is available to authorized users.