Effect of four antioxidants namely Di-potassium hydrogen orthophosphate (KaHPox). Aspirin (acetyle salicylic acid) ASA, Tartaric acid and Citric acid on damping- off, root rot, wilt and yield and it's attributes in sesame plants was investigated. Isolation trails from infected seedlings and plants showing symptoms of damping-oft. root rot, charcoal rot and wilt diseases yielded six soilborne fungi which were identified as Macrophomina phaseoiina (Tassi) Goid, Fusan'urn oxysporum (Schiecht.) f. sp sesami' Jacz, F. solanr' (Mart.)8acc, Rhizoctonia soianr' (Kuhn), Sclerotium roffssr'i (Secs). and Phytophthora parasitica Desi. The first two fungi were the most frequently isolated ones (35.3% and 22.4%), while P. parasitica was the least (6.4%). Linear growth values of M. phaseolina and F. oxysporum f. sp sesamr‘ were significantly reduced with specific rates of the tested antioxdants. All antioxidants showed less significant reduction in the growth of both fungi than control. The best reduction values of linear growth were obtained with Tartaric acid followed by Citric acid at 10 mM concentrations. Moreover. effect of the used antioxidants on pre -and post-emergence damping-off, charcoal rot, wilt, yield and yield attributes under greenhouse and field conditions during two successive growing seasons 2004 and 2005 at lsmailia Agricultural Research Station was tested. Six treatments for application methods were tested against disease incidence, yield and yield attributes under field conditions. Tartaric acid at 10 mM concentration was superior in minimizing disease incidence followed by Citric acid 10 mM, while Aspirin at 5 mM showed the lowest effect on the disease incidence. Among other antioxidants, KgHPos was the most effective on yield and yield attributes. The best treatment, viz. treatment of sesame seeds with seed dressing in the antioxidants and spraying the plants after one and two months from sowing also (83) was superior in minimizing diseases incidence and gave the highest values for number of capsules/plant, seed yield/plant and 1000-seed weight as the result of the interactions. Seed yieldffed was positive and highly correlated with the studied characters except oil percentage. Sesame seeds treated with any of the tested antioxidants increased peroxidase activity. The highest activity was obtained from plants grown from seeds previously treated with Tartaric acid followed by Citric acid at 10 mM concentration.