To evaluate effectiveness of pneumococcal polysaccharide vaccine, we recommended 1378 outpatients aged over 60 with chronic respiratory diseases to be vaccinated from August to October 2002, and 647 patients were vaccinated from August to November 2002. In the 1229 patients without respiratory failure, the incidence of antimicrobial treatment for bacterial respiratory infections in 547 vaccinated patients significantly decreased from 7.9% in the 2001/02 winter season to 5.7% in the 2002/03 winter season, although that in the 682 unvaccinated patients increased from 3.8% to 5.7%. The incidence of antimicrobial treatment for bacterial respiratory infections in 229 vaccinated patients with pneumococcal and influenza vaccines together significantly decreased from 10.5% in the 2001/02 winter season to 5.2% in 2002/03 winter season although that in 110 subjects vaccinated with influenza vaccine only increased from 2.7% to 7.2%. These findings suggest the effectiveness of the pneumococcal polysaccharide vaccine for the prevention of bacterial respiratory infections and the additive effectiveness of pneumococcal and influenza vaccines together.