The authors hypothesized that an audio-visual presentation providing information regarding the removal of an impacted mandibular third molar could improve patient knowledge of the surgical procedure and its possible complications. This possibly could decrease anxiety during the surgery. This randomized clinical trial included young adult patients who required surgical removal of an impacted mandibular third molar and fulfilled the predetermined criteria. Forty-two patients met the inclusion criteria; two patients refused to look at the audio-visual presentation. For both groups, heart rate (HR) was recorded beat-by-beat using an HR sensor (POLAR H1, UK) connected to an ActiGraph wGT3X-BT, USA. The Modified Dental Analogue Scale was used to subjectively record the anxiety during the surgery. Those who watched the audio-visual presentation before surgery had lower HR reading compared with those who received verbal instructions. These differences in mean HR reading were statistically significant for the following surgical stages: drilling, suturing, and leaving the clinic. The audio-visual informed group had lower self-reported anxiety scores than did the verbally informed group. These results suggested that providing an audio-visual presentation about the surgical procedures in our routine clinical practice could aid in alleviating anxiety and thereby reduce surgical complications.