Visiting anxious and fearful children is an inevitable prospect of the daily work of every dentist who treats pediatric patients. Dentists have been using a wide variety of non-pharmacological and some pharmacologic techniques to assist them in the management of children with anxiety. One strategy which seems promising for pain control in stressful medical situations is teaching the child to use behavioral and cognitive coping skills or a combination of both techniques. An alternative technique to non-pharmacologic approaches in children being anxious and lacking in cooperative ability is sedative technique such as nitrous oxide conscious sedation. As there is lack of studies comparing conscious sedation and combinations of cognitive-behavioral strategies in eliminating children's uncooperative behaviors and dental anxiety, the aim of this study was to compare the effectiveness of inhalation sedation with Nitrous Oxide-Oxygen conscious sedation and cognitive-behavioral therapy to reduce dental anxiety in preschool children.