Assafoetida is an oleo-gum resin obtained from the roots and stems of many Ferula species such as F. foetida Regel, F. asafoetida Linn, F. alliacea Boiss. and F. narthex Boiss, family Umbelliferae (carrot family), plants growing indigenously in Iran, Afghanistan and north of India. Assafoetida is commonly used as a flavoring agent in food and as a traditional medicine for many diseases in many parts of the world. In this work, the effect of Assafoetida on growth of Trichomonas vaginalis in vitro was studied and compared to metronidazole as a reference drug. It showed that Assafoetida had a potent antiparasitic effect on T. vaginalis compared to metronidazole, thus, worth further investigation to study its applicability in treatment of parasitic infections.