Objective To investigate the association between neuroticism and gastroesophageal reflux disease (GERD) using Mendelian randomization (MR). Methods Exposure and outcome data were downloaded from the IEU database (https://gwas.mrcieu.ac.uk/), containing summary statistics from genome-wide association studies (GWAS) for neuroticism (n=374 323) and gastroesophageal reflux disease (n=602 604). Using the weighted median (WM), MR-Egger, inverse variance weighted (IVW), weighted mode and simple mode methods for Mendelian randomization analysis. Odds ratio (OR) values were used to assess the causal relationship, while sensitivity analysis was used to ensure the accuracy of the results. ResultsNeuroticism (OR=1.229, 95%CI 1.186-1.274, P<0.001) was associated with an increased risk of GERD. Meanwhile, gastroesophageal reflux disease (OR=1.786, 95%CI 1.623-1.965, P<0.001) was also associated with increased risk of neuroticism. Conclusion The study finds a bidirectional causal relationship between neuroticism and gastroesophageal reflux disease.