During a period of observation of one year blood pressure was measured three times in the 0,6 th and 12 th months from a group of users of oral contraceptives (n = 377) and a reference group (n = 238) dependent from pregnancy-induced hypertension in women's history. Mean systolic blood pressure dropped in the group of oral contraceptive users by 0.7 mm Hg (0.1 kPa), diastolic blood pressure increased by 2.1 mm Hg (0.3 kPa) with significant difference vs. the reference group. Mean systolic blood pressure increased by 1.7 mm Hg (0.22 kPa) 6 months after using oral contraceptives in the group with pregnancy-induced hypertension (with significant difference). In the reference group without pregnancy-induced hypertension mean systolic blood pressure increased by 1.5 mm Hg (0.2 kPa) (without significant difference). Diastolic blood pressure values were not different. In the subgroup with pregnancy-induced hypertension history basal values of systolic and diastolic blood pressure distinctly were higher than in the control group.