Examinations during 3 consecutive years were made in Iowa for mold development in yellow dent shelled corn stored in steel bins of 1,000-2,740 bushel capacities. The first was made during August and September 1941, the second in March 1942 and the third in April 1943. Different bins were examined in each of the three inspections. Bins reportedly containing some corn of 14 percent or more moisture were examined and probed in the first examination, those with corn of 13.5 percent or more moisture in the second examination; no selection of bins for moisture content was made in the third examination. All of the bins examined had been filled during the fall previous to sampling.