StarLink disrupted the U.S. corn market during the 2000|01 marketing year as a result of inadvertent commingling. The potential, upper-bound volume of marketed StarLink-commingled corn from the 2000 crop located near wet and dry millers prior to October 1, 2000, is estimated at 124 million bushels. The percentage of corn shipments that tested positive mostly ranged from 5 to 10%, varying by mode of transportation. Price differentials between StarLink-commingled and StarLink-free corn commonly ranged between 7 and 12 cents per bushel during the early stage of the incident. These differentials eroded quickly due largely to Aventis' compensation of additional transportation costs when StarLink-commingled shipments had to be rerouted to approved uses. While StarLink had a negative impact on U.S. corn exports, most of the reductions in exports to Japan and South Korea during the period from November 2000 through March 2002 were due to increased competition from rival exporters. [EconLit citations: Q130, Q170]. © 2003 Wiley Periodicals, Inc. Agribusiness 19: 473-488, 2003.