tatement of Problem: Oral premedication used to reduce the anxiety in patients undergoing dental treatment. Passion flower has been used as a sedative that can control the dental anxiety.Purpose: This study determines the efficacy of Passion flower, in reducing anxiety during the dental procedures.Material and Methods: In this randomized- one sided blind clinical trial, 63 patients, with moderate, high and severe anxiety(according to VAS score)  in need of periodontal treatment were randomly divided into 3 groups of 21.The first group was given the drop  Passion flower drop and the second group were given the drop of placebo and  the third group; neither drug nor placebo were given (negative control group). Results were analyzed by Chi Square, Variance Analysis, Tucky and Paired-T using SPSS software.Results: Mean anxiety level prior to the drug administration was 12.09±2.42 for the Passion flower group, 12.00±2.66 for the placebo group and 11.66±2.39 for the negative control group. After premedication, these values were: 8.47±2.58 for the Passion flower group, 10.52±2.11 for the placebo group and 11.23±2.34 for the negative control group. These results demonstrated a significant difference (p< 0.0001) in the anxiety levels before and after the Passion flower administration in the Passion flower group and also between the Passion flower group and the other two groups.Conclusion: Results indicated that administration of Passion flower, as a premedication, is significantly effective in reducing the anxiety. Since this study is a pioneer on the subject, further trials with greater number of subjects are required to confirm our results.