The effect of newly synthesized derivative of 11-hydroxy-7-imino-7H-7a, 12-diazabenzo/α/anthracen-6-one, on growth and aflatoxin B1 and G1 (AFB1 and AFG1) accumulation by toxigenic mould Aspergillus fl avus ATCC 26949 was studied on a solid substrate (maize grains) to determine the possible use of this compound as a mean of controlling aflatoxin accumulation. Experiments were carried out in a stationary culture at temperature of 28oC during 21 days. The growth of mould was monitored by measuring the analysis of chitin as glucosamine, as a criterion, and concentration of AFB1 and AFG1 was measured by HPLC method using Hewlett-Packard instrument with fluorescence detector. Concentration of investigated coumarine of 0.05 mmol x g-1 stimulated mould growth and aflatoxin accumulation, but concentration of 0.2 mmol x g-1 or higher produced an inhibitory effect. In the presence of 0.2 and 0.5 mmol x g-1 of this compound, mould growth was decreased by 22% and 65%, respectively. Concentration of AFB1 in these investigations was reduced by 30% and 90%, and concentration of AFG1 was reduced almost completely in respect to values obtained in control experiments. In experiments with 2.0 mmol x g-1 of this inhibitor no synthesis of both investigated aflatoxins was found in the sample although small increment of biomass was detected.