To assess factors associated with influenza vaccination of healthcare workers. Cross-sectional survey. University-affiliated Veterans' Affairs medical center. Staff physicians and nurses employed by the medical center. A mailed, self-administered questionnaire. The response rate was 38.0%. The mean age of the respondents was 43.6 years, 71.5% were females, and 26.2% were physicians. Nearly all of the practitioners had daily or weekly contact with elderly or high-risk patients. The influenza vaccination rate of the respondents was 61.2%. More than 50% of vaccine recipients indicated that avoiding illness, protecting patients, and being able to receive the vaccine conveniently and free of charge all were very important factors influencing their decisions to receive the vaccine. Avoiding illness was rated the most important factor by 58.8% of vaccine recipients. Among vaccine nonrecipients, concern about side effects was identified as a very important factor by 36.2% and as the most important factor by 30.9%. Vaccine recipients were significantly more likely than were vaccine nonrecipients to indicate that influenza and its complications are very serious for high-risk patients. They also were more likely to report that the vaccine is very effective, that influenza vaccination is uncommonly associated with side effects, that healthcare workers' risk for contracting influenza is higher than the general public's risk, and that it is very important for healthcare workers to receive the vaccine to decrease risk for transmission to high-risk patients. After stepwise logistic regression, variables independently associated with receipt of vaccine were age, prior receipt of vaccine, being a physician, considering the vaccine to be very effective, believing that systemic side effects are uncommon, and indicating that it is very important for healthcare workers to receive vaccine for the protection of their patients. Many healthcare workers fail to receive influenza vaccine each year. Strategies to improve immunization levels should address concerns about vaccine safety and efficacy, barriers to vaccination including inconvenience and cost, and the reasons for targeting healthcare workers.