BACKGROUND: Scientific evidence from different sources suggests a positive association between sedentary behaviors and the incidence of hypertension. However, no previous prospective study corroborated this potential relationship in an adult population. Our objective was to assess prospectively the association of different sedentary behaviors (interactive and noninteractive sedentary activity, television viewing, and sleeping) with the incidence of hypertension. METHODS: In this prospective, dynamic cohort study (the SUN Study), 11,837 Spanish university graduates, with a mean age of 36 years, were followed for an average of 40 months, from 1999 to 2006. Sedentary behavior was assessed with a questionnaire at baseline, and the incidence of hypertension was assessed with validated, biennial questionnaires. RESULTS: We identified 291 new cases of hypertension among 6742 participants who remained after excluding those with self-reported hypertension, cardiovascular disease, diabetes, and cancer at baseline. Self-reported total sedentary behavior was directly associated with a higher risk of hypertension (hazard ratio, 1.48; 95% confidence interval, 1.01 to 2.18, comparing those in the upper and lower quartiles; P for trend = .03). In subtype analyses, interactive sedentary behavior (driving and computer use), but not noninteractive sedentary behavior (television viewing and sleeping), was associated with a higher risk of hypertension. CONCLUSIONS: Interactive sedentary behaviors appear to be an independent risk factor for incident hypertension. Noninteractive sedentary behaviors (television viewing and sleeping) did not show a significant association with incident hypertension.