Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (Sacc.) W.C. Synder and H.N. Hans is the major limiting factor in the production of tomato [1]. The pathogen occurs throughout most tomato-growing worldwide causing a vascular wilt that can severely affect the crop [2]. It is considered as one of the main soil-borne systemic diseases [3]. In this study, antifungal activity of essential oils of Cinnamon (Cinnamomum zeylanicum) and two fungicides Benomyl and Roval T-S in five different concentrations were investigated against Fusarium wilt disease of tomato in vitro and greenhouse conditions. In vitro, fungal radial growth for each concentration of essential oils and fungicides on pathogen was measured. In greenhouse, soil infested with F. O. f. sp. lycopersici was treated by adding 50 ml of different concentration of essential oils and fungicides. Disease severity was measured after four weeks. The chemical composition of the essential oils was determined by gas chromatography-mass spectrometry (GC-MS). Results of in vitro showed that plant essential oils of Cinnamon caused a significant decrease in the mycelial growth of F. O. f. sp. lycopersici. The mean EC50 value for plant essential oils on pathogen was 50.23 ppm. The profile of the plant essential oils of Cinnamon showed that Cinnamaldehyd (77.51%), ß-linalool (11.13%) and para methoxy cinnamic aldehyde (3.7%) were the main compounds. Microscopic observation shown morphological changes in hyphal cell of F. O. f. sp. lycopersici as discoloration and lyses of hyphe. In addition, the results of greenhouse indicated that plant essential oils significantly decreased disease severity and increased growth factors in tomato plants compared to control. Our results conclude that application of the plant essential oils of Cinnamon inhibited the growth of F. O. f. sp. lycopersici in vitro, and succeeded to control Fusarium wilt of tomato under greenhouse conditions. This finding suggests that the application of t
