The MICs of teicoplanin and vancomycin were determined for 400 penicillin-susceptible and -resistant strains of Streptococcus pneumoniae isolated during a multicenter study in 1992. Teicoplanin displayed a four-fold better activity than vancomycin, with modal MICs of these agents being 0.06 and 0.25 micrograms/ml, respectively. These data warrant further studies with teicoplanin in the treatment of pneumococcal infections.