The current status and future prospects of vaccines for adults are discussed. For every child in America who dies of a vaccine-preventable disease, about 400 adults die of such a disease. Evidence of the merit of influenza vaccination continues to accumulate, yet < 30% of high-risk people younger than 65 have been vaccinated. Use of pneumococcal vaccine lags behind that of influenza vaccine. Serious discrepancies in immunization levels exist among different segments of U.S. adult society. A vaccination status assessment is now recommended for everyone reaching the age of 50. New vaccines are available to prevent varicella, hepatitis A, and typhoid fever. There are now two formulations of hepatitis A virus vaccine; adult users of these vaccines include travelers, people relocating to areas with poor sanitation, military personnel, laboratory workers, and hemophiliacs. New rabies vaccines may be the next vaccines to be used primarily in adults. Vaccines against pertussis, Lyme disease, cholera, herpes simplex, malaria, other infectious diseases, and cancer are in various stages of development. For health care personnel in areas where there is a strong likelihood of Mycobacterium tuberculosis transmission and infection, BCG vaccination is recommended. The risk of immunization to a person infected with the human immunodeficiency virus is likely outweighed by the protection offered against other health threats. Health systems should select tetanus-diphtheria toxoids adsorbed for their formularies for immunizing adults, not monovalent tetanus toxoid. Vaccines are available to prevent a growing list of infectious diseases but are underused in adults.