HISTORY AND AIM: A 36-year-old woman (primigravida, nullipara) at 25 + 3 weeks of gestation and a 27-year-old (primigravida, nullipara) at 22 + 7 weeks of gestation presented with oligo-/anhydramnios at our department of obstetrics. Both patients suffered from diabetes type 1 and 2, respectively, complicated by diabetic nephropathy, renal hypertension and retinopathy. The first woman had received an AT1 receptor antagonist and a beta blocker, the other one an ACE inhibitor and a beta blocker. At initial clinical examination both patients were in a good general state of health. Respiration, pulse and blood pressure were within normal limits. METHODS Sonography showed oligy-/anhydramnion with enlarged echogenic kidneys of both fetuses. Having ruled out premature rupture of the membranes the reduced amount of amniotic fluid was interpreted as a consequence of the antihypertensive medication. METHODS The medication was changed to methyldopa which resulted in an adequate and moderate increase of amniotic fluid in both patients. At post partum examination renal failure was confirmed in both infants. The first infant, now a boy at the age of two years, still suffers from chronic renal failure, needing antihypertensive medication with an ACE blocker. Follow-up of the second baby has so far shown normal growth of the kidneys and normotensive blood pressure. CONCLUSIONS When planning a pregnancy, a preexisting hypertension should be treated with either methyldopa (1st choice) or a beta blocker as a second choice (e. g. Metoprolol). In patients who are treated with ACE blockers or AT1 antagonists, medication should be changed as soon as the pregnancy is ascertained.