Influenza and pneumococcal infections are important causes of hospitalization and death among individuals who are elderly or who have chronic illnesses. Influenza and pneumococcal vaccines may prevent these infections and their complications, but most high-risk patients have not received them. Doubts about their effectiveness, fears of side effects, and the lack of programs to promote their use contribute to the underuse of these vaccines. Although adequate controlled trials in high-risk patients are lacking, there is observational evidence that they are moderately effective, reducing serious complications of influenza and pneumococcal infections by about one-half. They are cost-effective compared with other preventive interventions and may be cost saving. Their safety has been demonstrated in numerous studies. Health care providers should promote influenza and pneumococcal vaccination. Strategies that have been shown to be successful in increasing the use of these vaccines include provider education and feedback, flagging charts of vaccination candidates, mailed reminders to patients without fall appointments, standing orders for nurses to administer the vaccines, walk-in vaccination clinics, and vaccination of hospitalized patients at discharge.