On July 16, 1999, CDC recommended that health-care providers suspend use of the licensed rhesus-human rotavirus reassortant-tetravalent vaccine (RRV-TV) (RotaShield, Wyeth Laboratories, Inc., Marietta, Pennsylvania) in response to 15 cases of intussusception (i.e., a bowel obstruction in which one segment of bowel becomes enfolded within another segment) among infants who received RRV-TV. The Vaccine Adverse Event Reporting System (VAERS) monitored for adverse events following licensure of RRV-TV on August 31, 1999. After the recommendation to suspend use of the vaccine, no additional cases were reported. This report describes the surveillance activities used to identify this vaccine adverse event, the emergency response, and follow-up investigations. Suspension of RRV-TV after the initial cases of intussusception parallels the removal of the Broad Street pump handle in response to John Snow's epidemiologic studies; both were decisive, life-saving public health actions.