A water flotation method was used to study the distribution of aflatoxin relative to kernel density in naturally contaminated samples of shelled farmers stock peanuts. Five-hundred gram samples of visibly undamaged, contaminated peanuts were added to 2000 mL of tapwater, and approximately 15–30% of the kernels rose to the surface as buoyant kernels. These buoyant kernels contained an average of 95 + % of the total sample aflatoxin content. Buoyant kernels, when examined internally, all had a hollow space or “lumen” inside the kernel between the two cotyledons. Data showed an association between aflatoxin content, kernel lumen volume, and the propensity of kernels to float. The lumen may provide a reservoir of air for flotation, fungal growth, and aflatoxin production. The positive association between the presence of a lumen and aflatoxin contamination may provide a possible resistance strategy, if the presence or absence of a lumen is genetically controlled or if it can be manipulated physiologically.