ACIP reviewed data on vaccine-related adverse events from the Vaccine Adverse Event Reporting System (VAERS). VAERS is a passive surveillance system jointly administered by CDC and the Food and Drug Administration that accepts reports from vaccine manufacturers, health-care providers, and vaccine recipients for vaccine safety. VAERS can be prone to overreporting or underreporting and inconsistency in the quality and completeness of reports. During September 2005–September 2010, a total of 243 VAERS reports were received regarding adults aged 65 years and older administered Tdap, out of 10,981 total VAERS reports on Tdap among recipients of all ages (CDC, unpublished data, 2010). Of the 243 reports regarding adults aged 65 years and older, 232 (96%) were nonserious. The most frequent adverse events after Tdap were local reactions, comprising 37% of all events. Eleven serious events were reported, including two deaths among persons with multiple underlying conditions. Although VAERS cannot assess causality, after review of data, it is unlikely the deaths were related to vaccine receipt. Postmarketing VAERS data also suggest that Tdap vaccine safety in adults aged 65 years and older is comparable to that of Td vaccine. Because Tdap is not licensed for use in this age group, comparisons between these reports and other reports need to be interpreted with caution.