Anxiety is a normal feeling which is experienced in threatening situations and can affect neural system. Balm (Melissa officinalis) is proposed in traditional medicine for adjusting the anxiety.This study was carried out to compare the effects of balm extract and diazepam on anxiety adjustment. 50 female were studied in five treatments groups including control, diazepam, 50, 100, and 200 mg/kg of balm’shydro-alcoholic extract. Drug and extract doses were injected IP. After receiving the lastdose, anxiety was induced using dark box and was evaluated byan elevated plus-maze. Frequency of entrance to open and close arms and also the spent time in those arms was measured as anxiety index. Hydro-alcoholic extract in 200 mg/kg dose increasedthe time of presence in open arms significantly which shows anxiety reduction. Also, movement activities of mice weresignificantly higher in this dose in proportion to diazepam. According to results, hydro-alcoholic extract of balm in 200 mg/kg dose can be good replacement for diazepam in reducing anxiety reflexes.