Despite well-documented evidence regarding effectiveness and safety, uptake of influenza vaccine among adults in the United States falls short of targeted rates.1,2 Efforts to increase influenza vaccine uptake have focused on reducing the number of so-called missed opportunities, ie, patients who visit health care providers during the fall without being vaccinated.1,3 Yet, the potential effectiveness of provider-based strategies for reducing missed opportunities (eg, standing orders, computerized reminders) may be overstated without consideration of patients' willingness to be vaccinated. We present a more realistic estimate of the potential of such strategies to increase influenza vaccine uptake by quantifying the number of unvaccinated adults most amenable to vaccination during a fall visit to a health care provider.