Objectives：I want to examine the antimicrobial activity of Gwankeibujalijung-tang against Streptococcus pneumoniae 59 isolated from the mouth of a common cold patient. Methods： Antimicrobial activity was assayed through the hot water extract from Gwankeibujalijung-tang against Streptococcus pneumoniae 59 isolated from the mouth of a common cold patient. Results： The size of inhibition zone of Gwankeibujalijung-tang extract was 9.83 $pm$ 0.11 mm. The optimal pH and temperature for the growth of isolated Streptococcus pneumoniae 59 were 7.0 and 37$^{circ}C$, respectively. The minimum inhibitory concentration of Gwankeibujalijung-tang extract was 12 $muell$ and the antimicrobial activity of Gwankeibujalijung-tang extract was not destroyed by the heat (121$^{circ}C$ for 15 min) and not affected by pH. Conclusions： Reviewing this experimental result, it appeared that Gwankeibujalijung-tang had efficacy against Streptococcus pneumoniae 59 isolated from the mouth of a common cold patient.