BACKGROUND: Given the high prevalence of esophageal adenocarcinoma and Barrett's esophagus (BE), a precancerous lesion, among males, it is important to understand the characteristics of BE by sex to develop an effective endoscopic surveillance program in Japan. The present study examined the age distribution and risk factors for BE in the Japanese health check-up cohort by sex. METHODS: The data set at baseline of our preceding multicenter study, comprising a total of 33,478 individuals who underwent upper endoscopic screening at 17 health check-up institutes across Japan, was utilized. BE and long-segment BE (LSBE) were defined as a columnar-lined esophagus ≥ 1 cm and ≥ 3 cm, respectively. Logistic regression analyses were performed to ascertain the factors associated with BE. RESULTS: BE was relatively common (10-20%) across all 10-year age groups in men and women. Although the prevalence of LSBE was rare (0.2%), it began to increase at younger ages in men. In the multivariable analysis of the male cohort, while body mass index (BMI) was negatively associated with BE with an adjusted odds ratio (95% confidence interval) of 0.84 (0.74-0.95), waist circumference (WC) was positively associated with 1.26 (1.13-1.41). Furthermore, this association was more pronounced in LSBE. In contrast, no such association was observed between BMI or WC and BE in women. CONCLUSION: The nationwide Japanese multicenter study yielded insights into the age distribution of BE in the Japanese population. Furthermore, our findings indicate that a low BMI/high WC represents a significant risk factor for BE in the Japanese male population.