In order to evaluate the antibody response to primary pneumococcal vaccination in the elderly, 20 healthy persons aged 60 years or older, (mean age 62.8) were vaccinated with a 23-valent pneumococcal polysaccharide vaccine (Pneumovax 23). Blood samples were taken before and 4 weeks after vaccination and pneumococcal antibody concentrations were measured by ELISA and compared with those obtained after vaccination of younger persons (mean age 39 years). Significantly lower anti-type 2 antibody concentrations were found in the elderly after vaccination. Apart from this, no other significant differences were found neither in pre- and post-vaccination antibody concentrations nor in antibody fold increases between the two groups.