Failure of medical advice by a medical practitioner can vitiate a patient’s consent to treatment giving rise to battery and it can also constitute a breach of the medical practitioner’s duty to inform bringing in negligence. This failure to inform pertains to the two torts of battery and negligence. What then is the distinction between medical trespass and medical negligence? The English cases from Chatterton v Gerson in 1981 to the recent leading case of Sidaway v Bethlem Royal Hospital Governors and Others have drawn a distinction. The distinction between the two torts is useful for the purposes of classification and application of tortious liability and is also necessary for the purpose of establishing the different functions of the two torts. Unfortunately, the distinction drawn is inappropriate. The article will first examine the distinction drawn by the cases between the two torts in this area of failure of medical advice; then it will discuss the difficulties in the distinction employed; and, finally, it will suggest a more appropriate relationship between medical trespass and negligence.