This report updates the last recommendations by the Advisory Committee on Immunization Practices (ACIP) concerning pneumococcal polysaccharide vaccine (MMWR 1989;38:64-8, 73-6). ACIP recommends that the vaccine be used more extensively and administered to all persons in the following groups: a) persons aged > or = 65 years, b) immunocompetent persons aged > or = to 2 years who are at increased risk for illness and death associated with pneumococcal disease because of chronic illness, c) persons aged > or = 2 years with functional or anatomic asplenia, d) persons aged > or = 2 years living in environments in which the risk for disease is high, and e) immunocompromised persons aged > or = 2 years who are at high risk for infection. This report contains updated information regarding a) antimicrobial resistance among pneumococci, b) vaccine effectiveness and cost-effectiveness, c) indications for vaccination, d) guidelines for revaccination, e) strategies for improving delivery of vaccine, and f) development of pneumococcal conjugate vaccine.