Doctors, like other professional people, are expected to exercise proper care in their work. If they neglect to do so and their patients are harmed they can expect to be criticised. Over the past decade, this criticism has increasingly taken the form of civil action against the doctor by patients or their families who seek financial recompense. More rarely, a patient dies as a result of alleged negligence and the Crown Prosecution Service considers that a criminal charge of manslaughter is justified. Up to 1990 these cases were very rare. In 1970, Leahy Taylor wrote that it was “unlikely in the extreme” that any doctor would face a charge of criminal negligence.1 He was aware of only two cases, those of Dr Percy Bateman, who had been convicted of manslaughter after an obstetric patient died, but was later pardoned on appeal,2 and a Dr Wight, who had been sentenced to 3 months' imprisonment for performing a forceps delivery while he was under the influence of chloral hydrate, as a result of which the mother died. In 1867 a Dr Spencer was acquitted of manslaughter after a medication error in which strychnine was dispensed to a patient instead of bismuth.3 This article focuses on errors in administering anaesthetics and in prescribing and giving medicines since these are the most common mistakes described in published reports.