The effect of drinking rhus tree-extract on performance of broiler was performed to investigate development of natural antibiotic in process of broilers production. A total of 320 broiler chicks at 1 day of age were fed the commercial diet and water, drinking water containing 0 ppm(control), 500 ppm (T1), 1,000 ppm (T2) and 2,000 ppm (T3) of rhus tree-extract fur seven weeks. The body weight gain and fred conversion ratio were not different by drinking rhus tree-extract until 35 days of age, but body weight gain and feed conversion ratio were tend to improve by drinking rhus tree-extract over 35 days of age, the improvement was higher in both T$_1$, and T$_3$ than control group(p＜0.05) when 35 to 42 days of age. There was a decrease in the microflora population of both E. coli. end Salmonella in the cecum contents and feaces in broilers by drinking rhus tree-extract. The digestibility of dry matter, crude fat, and crude ash of feed were tend to increased in broiler drinking rhus tree-extract. Digestibility of crude protein of feed in broiler three treated groups was significantly improved (p＜0.15) as compared with those in control group. These results indicated that the drinking rhus tree-extract were effective in the body weight gain, feed conversion ratio, decreasing of microflora population of both E. coli and Salmonella in the cecum contents and feaces, and it had also effective the digestibility of nutrients in broilers.