Using MIC as relative index, an observation was made on the growth inhibition of Staphylococcus aureus by Coptis alone or in combination with Scutellaria and or liquorice. The result shows that when Coptis is combined with Scutellaria, the bacteriostatic effect gets weaker for Scutellaria, but remains unchanged for Coptis, and when Scutellaria takes greater percentages in the combination, the effect of Coptis seems to be stronger. When Coptis is combined with liquorice, whatever the respective percentages may be, the effect tends to get weaker. When the three drugs are used in combination, the effect remains unchanged or even gets stronger for Coptis or liquorice, but tends to decrease for Scutellaria. Coptis used singly or in combination with Scutellaria or liquorice is inferior in bacteriostatic effect to the combination of the three drugs. The mechanism is yet to be further studied.