In the majority of dental schools there are insufficient numbers of clinical patients for all students to receive optimal experience in intravenous sedation. This investigation was carried out to assess whether the signs and symptoms for intravenous sedation taught to the undergraduates were sufficiently objective to ensure that this clinical deficiency was not detrimental to competency of the graduating student. The signs of ptosis, altered speech and blurred vision were used by both experienced dentists and novice students to assess the level of intravenous sedation. Blurred vision was found to be unreliable while altered speech was more accurate than ptosis. The more experienced the operator the earlier the signs were observed.The "Guidelines for the Teaching of Pain and Anxiety Control in Dentistry" were initially formulated by the American Dental Association in 1971 and revised in 1978(1) while similar guidelines were accepted by the House of Delegates of the Association of the Canadian Faculties of Dentistry in 1975(2) Both of these documents outlined the course of instructions necessary for the teaching of all modalities of pain and apprehension control at the undergraduate, postgraduate and continuing education level. Implementation of these guidelines at the undergraduate level has proven to be particularly difficult in the area of intravenous sedation because of the lack of suitable patients. This has resulted in many students graduating, having had little practical experience in sedating a patient with an intravenous drug. It is the hope of educators in this field that lectures, seminars, and demonstrations given to dental students are sufficient to overcome this deficiency.Since the most critical clinical aspect of intravenous sedation is titrating the amount of drug required without overdosing or underdosing the patient, it was decided to investigate this ability in students with no clinical experience with intravenous diazepam. Although many drugs and techniques are advocated(3,4,5) it was decided to limit the study to intravenous diazepam as it may be used alone and has a high therapeutic index.With the introduction of diazepam to clinical practice the symptomatology of the drug was established and described by clinicians.(6,7) Objective methods of measuring recovery from diazepam have been described by several authors(8,9,10) but the signs and symptoms used to assess the initial level of sedation have been subjective. This can be attributed to the fact that sedation is an ill-defined clinical effect and can, therefore, only be calibrated by individual arbitary signs. The most frequently used signs for intravenous diazepam sedation are ptosis, also referred to as "the Verrill sign,"(11) altered speech and blurred vision.(7) This investigation was designed to test the reliability of these signs and to examine the variability of observations between clinicians and students.