Production of aflatoxins B1, B2, G1, and G2in pure and mixed cultures ofAspergillus parasiticusandaspergillus flavuswere compared. Differing percentages of A.parasiticus(NRRL 2999) andA. flavus(NRRL 5520) conidia were used as inoculum and allowed to grow in static liquid culture for 10 days. The pure and mixed cultures of A.parasiticus/A. flavuswere extracted and the aflatoxins partially purified. High‐performance liquid chromatography was then used to determine aflatoxin concentrations. The maximal decreases of G1and G2production occurred when the inocula went from 0 to 12.5% or 25%A. flavus.Aflatoxins G1and G2comprised less than 10% of the total aflatoxins when the A.parasiticuslA. flavusinocula contained greater than 25%A. flavus.Production of aflatoxins B1and B2increased slightly as the percentage ofA. flavusin the A.parasiticuslA. flavusmixed inoculum increased.A. flavusis apparently capable of suppressing accumulation of aflatoxins G1and G2by A.parasiticuswhen these fungi are grown in mixed culture.