Accepted: 6 June 2022 Fungal pathogens are causative agent of pepper diseases that affect the yield loss. At least 10% of food loss in the developing country caused by plant diseases. Clove oil (Syzygium aromaticum L.) was reported to be able to control pathogenic fungi. In order to evaluate the effect of clove oil in inhibiting the growth of the pepper disease, three types of major causal agent of pepper diseases were used namely Colletotrichum acutatum, Phythopthora capsici, and Pythium sp. The experiment was evaluated in vitro. The three pathogens were treated with the essential oil in different concentration according to IC50 result on each fungi. The clove oil showed inhibitory effect against tested fungi. The Syzygium aromaticum L. essensial oil showed the best inhibitory effect at concentration 340 µl/L, 180 µl/L and 100 µl/L for C. acutatum, P. capsici, and Pythium sp. respectively.