Women with chronic hypertension or renal disease are at a particular high risk of developing pre-eclampsia or eclampsia. Pre-eclampsia is associated with an increased risk of fetomaternal complications. In women with uncomplicated mild and moderate hypertension, pregnancy is usually normal. Treatment of high blood pressure aims at reducing maternal cardio- and cerebrovascular catastrophies, and the benefit of the treatment must be weighed against possible harmful effects on the foetus. In some cases, antihypertensive treatment can be discontinued, or medication changed. Preconceptional counselling is important both for women with chronic hypertension and, even more so, for women with renal disease, since the outcome of the pregnancy may be affected by the underlying disease.