Orobanche aegyptiaca parasitize field, pasture, vegetable and many other plants by depleting their nutrients and water. O. aegyptiaca has special biological characteristics makk it difficult to control it in tha agricultural systems. Sesame( Sesamum indicum ) is an important oilseed crop in semi-arid areas such as Isfahan, Iran where O. aegyptiaca is one of its most common weeds. This research was conducted to determine the responses of various sesame genotype and O.aegyptiaca when planted together. Seeds of 11 Iranian sesame genotypes (Ardestan, Esfarayen, Oltan, Ahvaz, Borazjan, Darab-14, Ferdous, Kalat, Naz Tak Shakhe, Varamin and Yekta) and 10 foreign genotypes ( S16, S21, S23, S25, S4, S5, S6, S7, S8 and S9 ) were planted with the Orobanche seeds in pot. At flowering stage of sesame, tubercle number and dry weight, shoot number and dry weight and shoot height of O. aegyptiaca were determine. Leaf number, plant height and dry weight capsul number, seed number in capsul , 100-seeds weight, seed yield and root dry weight of sesame were determined at the physiology maturity stages. The results showed that various genotype responded differently to O.aegyptiaca . When planted with S9 genotype O. aegyptiaca produced the highest number of tubercles on the sesame root and the minimum shoot number suggests that this genotype could be used as both a trap crop and an O. aegyptiaca - resistant genotype. O. aegyptiaca produced the lowest tubercles and shoot number per pot when planted with the S7 genotype this genotype could be planted as an O. aegyptiaca -resistant genotypes. The Ardestan, Varamin and Ahvaz genotypes produced the highest yield, suggesting that these genotype could be tolerant to this weed. The results also showed that the activities of the antioxidant enzymes were different among the genotypes and suggesting that O.aegyptiaca infestation could stimulate plants antioxidant defense systems. The activities of catalaz, ascorbat peroxidase, gelotation peroxidase in the roots of Yekta. Varamin, S16, S25, Ardestan, Naz tak shakhe, Esfarayen, Ahvaz, S23, Darab14 and Ferdos were determind in order to examin possible relashion betwee the activities of these enzymes and visual score of leaf damage. Yekta, Varamin, S16 and S25 produced the highest level of ascorbate peroxidase, Varamin and Yekta genotype also produced maximum leaf number and height. Ardestan, Darab-14 and S16 genotypes produced the highest level of glutathione peroxidase and Ardestan and Esfarayen genotypes produced the highest level of catalase activity and Ardestan genotype also produced highest yield. The results suggested that the activities of enzayme could be used for selecting tolerant cultivars of sesame to orobanche however mechanism of the tolerant maybe different among the genotypes. Result of cluster analysis confirm that Iranian had different response to O.aegyptiaca infestation from those of foreign sesame genotypes and they classified into 4 groups. According to results of this experiment, all esame genotypes as a trap crop or host plant with the root exudates could be caused germination of O. aegyptiaca . ome of the sesame genotypes enhanced germination, seedling establishment and development of O. aegyptiaca , so based on the results of this research, sesame can be considered as a host plant for the O. aegyptiaca .