Objective: To evaluate the prevalence of hypertension by different criteria in a young adult population assisted by a Family Health Program unit in Rio de Janeiro – LapARC cohort study. Design and method: This is a cross-sectional population-based study enrolling young adults aged 20–50 years, previously registered in a Family Health Program unit located in the center of Rio de Janeiro. It was approved by the institution's ethics committee. A database was built with each subject's sociodemographic characteristics, traditional cardiovascular (CV) risk factors and anthropometric measurements. The subjects considered hypertensive had office blood pressure (BP) >= 140x90 mmHg (old criteria) or >= 130x80 mmHg (new criteria). Patients with systolic BP between 130–139 mmHg and diastolic BP between 80–89 were classified as stage I and BP >= 140x90 mmHg as stage II. The office BP considered was the mean between two consecutive readings. Reference values used for HBPM were <= 130x80 mmHg. Continuous data was compared using One-Way ANOVA, Student t-test and Mann-Whitney test and categorical data, chi-squared test. Logistic regressions were used to assess the independent correlates of hypertension stages. Results: A total of 472 individuals were evaluated (mean age of 38 years). According to the old criteria, 23.1% of the subjects had hypertension (HT), however, considering the new criteria, it rose to 40.7%. The variables independently associated with stage I HT were abdominal and neck circumference, male sex and age >39 years. Of those, 316 individuals underwent HBPM and a total of 14% had white coat HT and 7%, masked HT. The only variable independently associated with uncontrolled home BP was obesity. People with white coat HT were more frequently male with higher neck circumference. Masked and sustained HT was more prevalent among the more obese with higher neck and abdominal circumference. Conclusions: Evaluating this population in the light of the new criteria, the prevalence of HT nearly doubled, and subjects classified as stage I appear to have higher CV risk when compared to the group with normal BP. Moreover, 21% of the diagnoses changed after HBPM, emphasizing the importance of out-of-office BP measurement.