Four peanut genotypes, selected as resistant to invasion by Aspergillus flavus in laboratory screening with rehydrated, stored seed and Florunner cultivar were subjected to preharvest drought and temperature conditions conducive to A. flavus invasion and aflatoxin contamination. Preharvest aflatoxin contamination of peanuts has been previously correlated with geocarposphere temperature and moisture conditions during drought. All genotypes tested were highly contaminated with aflatoxin. This study indicates that a critical assessment should be made of the value of using the current laboratory method to select germplasm for resistance to A. flavus invasion and assuming resistance to aflatoxin contamination under field conditions.