Abstract: A method for quantitatively determining the extent of mold contamination of grain and other mold-susceptible bulk food. The mold spores are selectively extracted from a small representative sample of the grain or other food by admixing with a solvent. After washing with a detergent, the extracted spores are suspended in a sterile solution and, in the case of heavy contamination, a series of graduated dilutions of known concentration are prepared. A measured sample of suspended spores is transferred to a nutrient growth medium and maintained under growth conditions until all possible spore colonies have developed. The spore colonies are counted. Since the dilution factor is known, the number of fungal spores in the original sample of stored product can readily be calculated.