OBJECTIVE The National Health Service Litigation Authority has issued a warning about the process of asking a patient for their consent prior to a medical procedure. This warning was issued in the light of the case of Chester v. Afshar. For the first time in English law the courts have appeared to state that failure to give a patient adequate information about a procedure is negligent per se. This article briefly examines the history of consent since the famous case of Bolam and reviews the recent legal commentary on the case of Chester. It will also consider a proposed solution to the question 'What is adequate information?' RESULTS The medicolegal literature traces the change in the legal test used to determine whether a patient has been adequately informed. It charts the evolution of a 'prudent patient' test and suggests ways in which medical practitioners might adequately fulfil their duty to inform patients properly. CONCLUSIONS Since the case of Chester v. Afshar it has become harder for a doctor to escape a charge of negligence if they have given inadequate information at the time of asking a patient for their consent to undergo a medical procedure. It is in everyone's interests - doctor and patient - to make the process of consent transparent and to an agreed national standard.