Aflatoxins are problematic in groundnut due to infection of Aspergillus flavus L. Ex. Fries. In this context survey was conducted in 14 districts of Karnataka, India to assess the severity of A. flavus. The results revealed high incidence in Belligatti (taluk and dist- Dharwad) when assessed on agar plate. It was also found high in two other samples (Davanagere and Tumkur) by subjecting to blotter test. In samples collected from market, higher incidence of A. flavus was observed in Dharwad and Hubli. Aspergillus flavus produced greenish to brownish colonies, the conidia were pyriform to globbose, varied in size (8 x 7 to 5 x 4 mm). The fungus produced larger colony on potato dextrose agar and smaller one on host extract agar. In inoculated seeds, the infection led to the reduction in sugars (reducing, non-reducing and total sugars), proteins, oil content and seed germination.