Millions of doses of influenza vaccine are administered each year in the United States at nontraditional sites and by nontraditional vaccine providers. Pharmacists are increasingly becoming vaccine providers. To measure association between availability of pharmacist-immunizers and immunization delivery to adult prescription recipients, and the relative contributions of various types of vaccine providers. Mailed survey in spring 1999, contrasting adults in urban Washington State, where pharmacists administer vaccines, to adults in urban Oregon, where pharmacists did not. Cluster sample based on October 1998 prescription records suggesting need for influenza vaccine, derived from 24 community pharmacies belonging to one pharmacy chain. Vaccination status and choice of vaccine provider. Influenza vaccination rates among respondents 65 years or older increased 4.7% more in Washington than in Oregon between 1997 and 1998 (P = 0.20). The net increase in influenza vaccination rate among younger respondents taking indicator medications for chronic diseases for which influenza vaccination is recommended was 10.6% (P = 0.05). Among respondents unvaccinated against influenza in 1997, the 1998 influenza vaccination rate was 34.7% in Washington, compared with 23.9% in Oregon (P = 0.01). Vaccine delivery by pharmacists is associated with higher rates of vaccination among those younger than 65 taking indicator medications medications for chronic diseases, as well as prescription recipients unvaccinated against influenza in the previous year.