OBJECTIVE:The mechanism by which recurrent croup occurs is unknown. Gastroesophageal reflux is commonly implicated, although this relationship is only loosely documented. We conducted a systematic review with a meta-analysis component to evaluate the relationship between recurrent croup and gastroesophageal reflux disease (GERD), and to assess for evidence of improvement in croup symptoms when treated. STYLE DESIGN:Systematic Review and Meta Analysis. METHODS:We searched five separate databases. Studies were included if they discussed the relationship between croup and GERD in children, >5 subjects, and available in English. Literature retrieved was assessed according to pre-specified criteria. Retrieved articles were reviewed by two independent authors and decisions mediated by a third author. If there was a difference of opinion after first review, a second review was performed to obtain consensus. Heterogeneity was calculated and summarized in forest plots. RESULTS:Of 346 initial records, 15 met inclusion criteria. These were two retrospective cohort and 13 cross-sectional studies. Thirteen of 15 articles support an association between recurrent croup and GERD. Although heterogeneity is high among studies that reported prevalence of GERD, there is less uncertainty in results for improvement to recurrent croup after GERD treatment. Most studies lacked a control group and all carry a moderate-to-high risk of bias. CONCLUSION:There is limited evidence linking GERD to recurrent croup; Further research is needed to assess for causality as most studies are retrospective, lack a control group, and have a study design exposing them to bias. Patients treated with reflux medication appear to demonstrate a reduced incidence of croup symptoms. LEVEL OF EVIDENCE:1 Laryngoscope, 131:209-217, 2021.