Vaccination is one of the greatest advances in medical history. Continued improvements in vaccination will include the introduction of new vaccines and the improvement of the efficacy and safety of existing vaccines. This report analyzes the 8623 reports made to the Vaccine Adverse Events Reporting System from the state of Texas from 1991 through 1999. The severity, time of onset, and vaccine type of the reactions, as well as the sex and age of those affected, were examined. Physicians and other health care providers need to be vigilant in their reporting of adverse reactions to vaccines. Persons injured by vaccination should be referred to the National Vaccine Injury Compensation Program.