Since the introduction of angiotensin converting enzyme-inhibitors (ACE-inhibitors) in the 1980's, more than 50 cases of foetotoxic effects ascribed to intrauterine exposure to inhibitors have been published. Among the most commonly reported effects are: Hypotension, renal dysplasia, anuria/oliguria, oligohydramios, intrauterine growth retardation, pulmonary hypoplasia, unclosed ductus arteriosus, incomplete ossification of the skull, intrauterine og neonatal death. Recent animal studies have confirmed that intrauterine or neonatal exposure to ACE-inhibitors or the AT1-receptor antagonist losartan can cause death and serious, irreversible organ damage. These effects are similar to the complications previously reported in humans. Animal studies suggest that the foetotoxic actions are most common after exposure during the last trimester. However, due to the severity of these complications, the use of ACE-inhibitors and AT1-receptor antagonists should be avoided throughout pregnancy and in women who are breast feeding.