This is a partly randomized open-label study in healthy postmenopausal women. Groups are treated in the following sequence: first a 2 mg estetrol group together with a 2 mg estradiol group. When the dose of 2 mg estetrol is safe and the tolerability is good, a next higher dose group of estetrol will start, possibly followed by two next higher dose groups if the previous dose group is safe and the tolerability is good.