Fifty-eight strains of Aspergillus spp. isolated from various grains were examined for the screening of aflatoxins by the method of the Thin-Layer Chromatography (TLC), using the aflatoxin producing strain of Aspergillus flavus ATCC 15517 as a control. The results as follows: 1. Samples of Aspergillus spp. isolated from various grains were extracted with chloroform and chromatographied by the thin-layer chromatography method. 2. Three strains of Aspergillus spp. among the 58 strains can be found that the spots having the same Rf value as control with culture extract of Aspergillus flavus ATCC 15517. 3. The further prove studies of aflatoxins were proceed by the methods of in vivo and in vitro tests. And this methods considered to capable for the use of mass screening among the samples.