On January 3, 2003, the Michigan Department of Agriculture's (MDA) Food and Dairy Division and the U.S. Department of Agriculture (USDA) were notified by a supermarket of a planned recall of approximately 1,700 pounds of ground beef because of customer complaints of illness after eating the product. On January 10, the supermarket notified MDA that their laboratory had determined that the contaminant in the ground beef returned by customers with reported illness was nicotine. This report summarizes the investigation of these cases, which identified approximately 100 affected persons, and discusses actions taken to prevent additional illness, including the arrest of a person charged with deliberately poisoning the ground beef at the supermarket.