Blood pressure in women rises after menopause. In the same period of their lives many women gain weight. Both menopause and increases in body weight may influence blood pressure elevation. To study the association between changes in body weight, age at menopause and duration of menopause, and blood pressure, a prospective follow-up study was conducted in 1167 Dutch women initially aged 45-64 years. After an average follow-up period of 8.9 years 855 women, of 1009 alive at that time, were re-examined (85%). This study indicated that age at menopause and number of postmenopausal years are not directly related to blood pressure rise in middle-aged and elderly women. However, an increase in the body mass index is an important and potentially preventable determinant of increased blood pressure and incidence of hypertension in women of this age group.