Objective : I want to examine the antimicrobial activity of Samhwangsasimtang against pseudomonas aeruginosa 38 isolated from an acne patient. Method : Antimicrobial activity was assayed through the hot water extract from Samhwangsasimtang against pseudomonas aeruginosa 38 isolated from an acne patient. Result : The size of inhibition zone of Samhwangsasimtang extract was $12.6;{pm};0.04;mm$. The optimal pH and temperature for the growth of isolated pseudomonas aeruginosa 38 were 6.0 and $37^{circ}C$, respectively. The minimum inhibitory concentration of Samhwangsasimtang extract was $10;{pm};0.06;{muell}$ and the antimicrobial activity of Samhwangsasimtang extract was not destroyed by the heat ($121^{circ}C$ for 15 min) and not affected by pH. Conclusion : Reviewing this experimental result, it appeared that Samhwangsasimtang had efficacy against pseudomonas aeruginosa 38 isolated from an acne patient.