Acute hepatic porphyrias are inherited disorders of heme biosynthesis. A characteristic feature of acute porphyrias is the occurrence of acute attacks which are often precipitated by drugs. Many of the commonly used anaesthetic agents may trigger such a potentially lethal attack. Thus, only safe agents should be administered to predisposed patients. Recommendations given are based on results from animal experiments and on a series of anecdotal reports. Regional anaesthesia is presented as anaesthetic technique of choice. General anaesthesia should be based on a fentanyl-nitrous oxide regimen, with propofol as induction agent. In the case of an acute attack, treatment consists of glucose and haematin administration.