A few studies have associated vitamin D deficiency with the occurrence of recurrent aphthous stomatitis (RAS). Hence, the aim of the present systematic review and meta-analysis is to explore such a potential association.A comprehensive search of PubMed, Scopus, and Web of Science databases was conducted in June 2019.The inclusion criteria were: 1) observational studies that assessed the relationship between vitamin D and RAS, and 2) the outcome measures reported quantitative vitamin D levels. Studies without control groups, case series, case reports, experimental studies, letter to editors, reviews, were excluded. The random-effects model was conducted for meta-analyses using RevMan 5.3 software.Five studies comprising 208 RAS patients and 241 healthy individuals were included. All studies except one reported significantly lower levels of vitamin D in RAS patients compared to the healthy individuals. The results of the pooled 5 studies revealed statistically significant lower levels of vitamin D in RAS patients (Mean Difference (MD) = -9.67 ng/mL, 95% CI= -15.68, -3.65; P ˂ 0.002).The present meta-analysis suggests a significant association between low vitamin D levels and RAS. Further well-designed studies with adequate sample sizes are required to elucidate the role of vitamin D in pathogenesis of RAS. This article is protected by copyright. All rights reserved.