Personality affects fundamental behavior patterns and has been related with health outcomes and mental disorders. Recent evidence has emerged supporting a relationship between the microbiota and behavior, referred to as brain-gut relationships. Here, we first report correlations between personality traits and gut microbiota. This research was performed using the Revised NEO Personality Inventory and the sequencing data of the 16S rRNA gene in 672 adults. The diversity and the composition of the human gut microbiota exhibited significant difference when stratified by personality traits. We found that personality traits were significantly correlated with diversity of gut microbiota, while their differences were extremely subtle. High neuroticism and low conscientiousness groups were correlated with high abundance of Gammaproteobacteria and Proteobacteria, respectively when covariates, including age, sex, BMI and nutrient intake, were controlled. Additionally, high conscientiousness group also showed increased abundance of some universal butyrate-producing bacteria including Lachnospiraceae. This study was of observational and cross-sectional design and our findings must be further validated through metagenomic or metatranscriptomic methodologies, or metabolomics-based analyses. Our findings will contribute to elucidating potential links between the gut microbiota and personality, and provide useful insights toward developing and testing personality- and microbiota-based interventions for promoting health.