Abstract: Aspergillus flavus isolated from 51 foodstuff samples was screened for aflatoxin production by TLC. It was found that 26.1% of the total isolates were toxic strains and the main toxin was found to be aflatoxin B1. Of 46 foodstuffs commodities surveyed for natural contamination with aflatoxin by HPLC method, 26.1% of the samples were found to contain the aflatoxin and the most contaminated samples were poultry feed, cereal grains and oil seeds. The presence of four aflatoxins B1, B2, G1 and G2 was detected only in two of the tested samples. Bioassay of a toxigenic A. flavus strain (AFB2) had been done on four different types of three seeds and grains, using four different soaking intervals 3, 6, 12 and 24 hours on culture filtrate of the fungus. Germinability of cow pea and chick pea had vigorously reduced when soaked on culture filtrate of the toxic isolate of A. flavus. Broad bean and maize were the most affected since the germination percentage were 0% and 15%, respectively. The toxigenic isolate (AFB4) was used to detect their toxicity on 14 fungal and bacterial species. The toxigenic isolates inhibited the growth of two fungal species (A. flavus and Penicillium digitatum) and two bacterial species (Klebsiella oxytoca and Staphylococcus aureus).