BACKGROUND: Few of studies investigated the effect of antihypertensives among working population. We aimed to describe the impact of hypertension with and without antihypertensives on hospitalizations because of cardiovascular diseases (CVDs) in the Japanese working population. METHODS: This retrospective study included adults aged 40-64 years whose systolic and diastolic blood pressure (BP) readings taken between 2008 and 2015 were available in the Japanese claims database. Individuals were categorized as treated (T) or untreated (UT) depending on their hypertension treatment history. Time to first CVD-related hospitalization was compared among individuals with different BP levels using Cox models that included baseline characteristics with either baseline BP level or a time-dependent variable reflecting BP changes over time. RESULTS: Of 740,784 UT individuals (male: 61.9%, mean age: 47.9 years), 2,121 individuals were hospitalized due to a CVD over a 957.3-day average follow-up. Among 72,828 T individuals (male: 74.3%, mean age: 53.7 years), the corresponding figure was 470 individuals over an 813.4-day average follow-up. The risk of hospitalization increased with baseline hypertension severity among UT (hazard ratios [HRs] = 1.93, 2.82, and 6.32 for grade 1, grade 2, and grade 3, respectively; P < 0.0001, reference: optimal) but not among T individuals. UT individuals with hypertension at any given time had a significantly higher probability of hospitalization compared to nonhypertensive individuals (HR = 1.74, P < 0.0001). CONCLUSIONS: This study adds quantitative evidence on the impact of hypertension on the risk of CVD-related hospitalization in the Japanese working population. It suggests that antihypertensive treatment had beneficial effects in this relatively young, working population aged 40-64 years.