Myomas are the most common benign tumors of the uterus. The role of inflammatory processes in myoma growth has led to the selection of Mullein (Verbascum Songaricum) for the treatment of myoma due to its potent anti-inflammatory properties. This study was conducted to evaluate the effect of oral Mullein capsule on asymptomatic uterine leiomyomas volume and the amount of menstrual bleeding. In this two-parallel arm triple-blind, randomized, controlled trial, 50 women were selected among women referred to the clinics affiliated to Tabriz University of Medical Sciences aged 18-50 years old, having at least one asymptomatic myoma greater than 2.5-cm, in Iran over 2017-2018. The participants were randomized into two groups. The first group (n=25) received 400 mg of Mullein powder capsules and the second group (n=25) received placebo capsules twice a day for 8 weeks. The mean volume of the largest myoma indicated no statistically significant difference (adjusted mean difference (aMD) = -7.6 ml, 95% CI: -22.0 to 6.6). Within-group analysis of the largest myoma volume showed a significant reduction in the Mullein group (MD = -6.8 ml, 95% CI: -13.0 to -6.3(. There was no significant difference in the first (aMD=1.3, 95% CI: -24.3 to 27.0) and second (aMD =7.3, 95% CI: -12.6 to 27 .2) cycles regarding the amount of menstrual bleeding. The results of this study showed that treatment with 800 mg of oral Mullein capsules per day for 2 months did not influence the myoma size, and amount of menstrual bleeding, although there was a significant reduction in the size of myoma in the Mullein group.