Wound swabs and pus samples were collected from diabetic foot ulcers, and control pus samples from non-diabetic cases. In 144 diabetic cases screened, Pseudomonas aeruginosa was isolated from 78 cases, in which 10.59% of the isolates were multidrug resistant (MDR), whereas the 60 control cases were not MDR. The isolated bacteria were decreasingly resistant to 6 clinically administrated antimicrobics such as ceftazidime, gentamicin, ciprofloxacin, tobramycin, piperacillin and amikacin. Therefore, it is demanded that new and more effective antimicrobials of phytochemical origins are sought after. Among 11 isoflavones (YS11-YS21) isolated from Sophora and Euchresta (Leguminosae; pea plant family), 2 (YS19 and YS21) prominently exhibited the high antibacterial activity both in vitro and in vivo. By the preliminary results, the object of this paper is to evaluate the in vitro antibacterial effect of YS19 and YS21 on the clinically isolated bactera of Ps. Aeruginosa in hospitals. All the isolates were sensitive to YS19 and YS21 and for both, minimum inhibitory concentration (MIC) values ranged from $2;to;50;{mu}g/mL$. The $MIC_{90}$ values of YS19 and YS21 were $50;{mu}g/mL$. It is suggested that these isoflavones might consist a basis phytochemical prevention and therapy for diabetic foot infections caused by pseudomonads.