Contamination of peanut (Arachis hypogaea L.) with aflatoxin produced by species of Aspergillus remains a problem for the U.S. peanut industry. Several peanut genotypes were reported to be resistant to in vitro seed colonization by Aspergillus flavus Link ex Fries (IVSCAF), to field seed colonization by A. flavus (FSCAF), or to preharvest aflatoxin contamination (PAC), but few to production of aflatoxin per se. Cotyledons of 39 peanut genotypes reportedly resistant to IVSCAF, FSCAF, or PAC, and eight susceptible to PAC were evaluated in four tests for their ability to support aflatoxin production after inoculation with A. flavus. Cultivars Perry and Gregory were used as checks in each test. Seed cotyledons were separated, manually blanched, inoculated with conidia of A. flavus, placed on moistened filter paper in petri dishes, and incubated for 8 d at 28 C. Dishes were arranged on plastic trays enclosed in plastic bags and stacked with PVC spacers between trays. Incomplete block designs were used for all tests. In each test, none of the genotypes examined was completely resistant to aflatoxin production, but significant genotypic variation was observed in the amount of total aflatoxin accumulated in seeds. Genotypes previously reported to be resistant to IVSCAF, FSCAF, or PAC exhibited differential abilities to support aflatoxin production. PI 590325, PI 590299, PI 290626, and PI 337409 supported reduced levels of aflatoxin, and their degree of resistance was consistent across tests. Fungal growth was highly correlated with aflatoxin production in three tests. The results from this study suggested that there were no absolute relationships of aflatoxin production resistance with IVSCAF, FSCAF, or PAC resistance, but that it should be possible to identify a genotype with high IVSCAF, FSCAF, or PAC resistance and reduced capacity for aflatoxin production by A. flavus.