Two experiments were conducted to investigate the influence of dietary supplemental Enviro on noxious gas of environmental controlled poultry house and performance of broiler chicks. Diets contained 21.5, 19.00 CP and 3,100, 3,200 kcal/kg ME, respectively for starting and finishing period. Enviro were supplemented with 0, 0.2, 0.4, 0.6 and 0, 0.1, 0.2, 0.3% in Expt. 1 and 2, respectively. $CO_{2}$ and ammonia gas were periodically detected for finsihing period in Expt. 1. Weight gain, feed intake and feed conversion(FC) were measured for five weeks in Expt. 2. ND antibody titer were also measured after primary and booster vaccination at two and three weeks old. Blood cholesterol and nutrients digestibility were In Expt. 1, ammonia and $CO_{2}$ gas of chicks fed 0.2% Enviro showed 32.8ppm and 1,719ppm in poultry house and significantly decrease compared to that of control(P〈0.05). $CO_{2}$ gas was 1,814ppm in 0.4% Enviro treatments and also significantly lower than control(P〈0.05), but tended to be increased compared to that of 0.2% Enviro treatments, In Expt. 2, weight gain of chicks fed 0.1 and 0.2% Enviro was significantly increased for starting period(P〈0.05), but was not statistically different for finishing period. Feed intake was no significantly different of all treatments. Chicks showed lower FC in 0.3% Enviro treatment for starting period(P〈0.05) than others, but was not for finishing period. ND AB titer of chicks fed Enviro was prone to be higher than control, but was not significantly different. Total blood cholesterol was not significantly different of all treatments, but tended to be high in 0.1 and 0.2% Enviro treatments. HDL of chicks fed those levels showed significantly higher than control(P〈0.05), whereas LDL was tended to be decreased in those treatments. The digestibilites of crude protein and fiber were improved in 0.1 and 0.2% Enviro treatments relative to those of control, but was not statistically different. However, crude ash digestibility was significantly improved in 0.1 and 0.2% Enviro treatments(P〈0.05). Chicks also showed AMEn in 0.1, 0.2% Enviro treatments, but was no significance. The results of these experiments indicated that 0.1% Enviro supplement would be maximize the performance of broiler chicks.