OBJECTIVES: It is not yet clear whether dietary protein could help healthy blood pressure (BP). We investigated the association between protein intake, estimated from 24-h urinary urea excretion, and incident hypertension in Dutch men and women. METHODS: We analyzed data of 3997 women (aged 28-75 years) who participated in the Prevention of Renal and Endstage Disease (PREVEND) study, a prospective cohort study. Urea assessed in two consecutive 24-h urine collections at baseline and 4 years later, from which total protein intake was estimated using the method. Participants were followed for 9 years for hypertension defined as BP at least 140/90 mmHg or initiation of antihypertensive Hazard ratios (HR) were obtained in sex-specific quintiles of protein using time-dependent Cox regression, adjusted for age, sex, BMI, use, and 24-h urinary excretions of sodium and potassium. RESULTS: was on average 119/70 mmHg and 976 participants developed hypertension follow-up. Mean protein intake (in g/kg ideal body weight) was 1.18 +/- men and 1.12 +/- 0.25 for women. Estimated protein intake was inversely associated with incident hypertension in the fully adjusted nonsignificant HR of 0.77, 0.75, 0.82, and 0.83 in consecutive quintiles with the lowest quintile (P-trend: 0.52). CONCLUSION: Protein intake, as by urinary urea excretion, was not significantly associated with 9-year hypertension incidence in Dutch men and women.