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This issue of the Canadian Journal of Anaesthesia contains the article by Crawford et al. entitled "Haemodynamic and organ blood flow responses to sevoflurane during spontaneous ventilation in the rat: a dose response study." The salient point of the paper is the conclusion that in this model, sevoflurane maintains both cardiovascular stability and organ blood flow to a remarkably salubrious degree. Other investigations have produced similar results in animals attesting that this inhalational anaesthetic appears to produce less cardiovascular sequelae than other inhalation anaesthetics at equipotent concentrations. The readers may well query "if this inhalation anaesthetic is so good, where has it been all these years?" Sevoflurane has been knocking around for over 15 yr since first synthesized and described by Wallin etal. l from Baxter-Travenol laboratories. The first volunteer trials (Phase I trials) were conducted by Holaday and Smith 2 over ten years ago. These trials proceded very well and the investigators gave sevoflurane high marks at this early stage. Analysis of the reasons why the halogenated inhalation anaesthetic is not now available for clinical use is complex. Sevoflurane received early investigative interest about the same time that isoflurane was in its last stages of development. On the surface, isoflurane had many salient features to recommend it over sevoflurane, a potential commercial as well as clinical rival. First, isoflurane is biotransformed to a far lesser extent than sevoflurane. Approximately 1% of absorbed isoflurane is metabolized contrasted to approximately 3% sevoflurane. Since isoflurane was marketed to replace enflurane (also metabolized to a degree similar to sevoflurane), the lack of biotransformation of isoflurane was a cardinal virtue promoting acceptance by anaesthetists. This, after all, was the decade in which biotransformation of halogenated anaesthetics was determined to be a b~te noire. Methoxyflurane renal toxicity and halothane hepatic toxicity had been coupled to breakdown of the anaesthetic molecules by the liver to undesirable products. Another di s