Greenhouse and field experiments were conducted in 2007 and 2008 to study the effect of some heavy metal concentrations, cobalt sulfate (Co++) at 0,0.25,0.50,1.0,2.0,4.0 and ferrous sulfate (Fe++) at 0,50, 100,200,400 and 800 ppm on incidence of peanut pod rots, occurrence of Aspergillus flavus Link and determination of aflatoxins content. Treated with Co++ and Fe++ showed a significant reduction of pod rot diseases incidence, A. flavus frequency, aflatoxins content and increase of total peanut yield. The highest reduction in incidence of pod rots and increase in pod yield were detected with Fe++ (400 ppm) followed by Co++ (2.0 ppm) during the two growing seasons 2007 and 2008. Treating with Co++ was more efficient in decreasing the A. flavus frequency and aflatoxin contaminations than Fe++ treatment. Increase the concentrate of the heavy metals gave more decrease for A. flavus occurrence and aflatoxins content in seeds.  Spraying with Fe++ increase phenol contents (free, conjugate, and total phenols) and oxidative enzymes (peroxidase, polyphenol oxidase and catalase) than the untreated (control). While, Co++ treatment decreased the activity of oxidative enzymes and content of phenol compounds. Data obtained from the electrophoretic banding patterns of proteins extracted (SDS-PAGE) showed that, there are six polymorphic bands within all Co++ treatments (molecular weights 25,29,38,48,50 and 54 KDa) which its distinction the Co++ treatments and may be have a role in the resistance.  Regard to the impact of these metals concentrations on content of peanut seeds from Co and Fe Data showed that Co++ treatments perform to decrease the amount of Fe++ in peanut seeds and increasing the concentration of heavy metals performed to increase its amount in peanut seeds but this increment still in the save limit of general healthy.