The Advisory Committee on Immunization Practices (ACIP) has issued recommendations previously for use of smallpox vaccine and supplemental recommendations for use of smallpox vaccine in the pre-event civilian vaccination program. On March 28, 2003, CDC reported cases of cardiac adverse events among persons vaccinated recently with smallpox vaccine. In response to these reports, ACIP held an emergency meeting on March 28 to make recommendations to CDC about medical screening of potential vaccinees and follow-up of persons with cardiovascular risk factors after vaccination. These recommendations supplement those previously issued by ACIP.