An experiment was conducted to investigate the effects of supplementary Blended essential oil(CRINA$^{circledR}$) on the performance, nutrient availability, fatty acid composition of leg muscle, small intestinal microflora and blood parameters in broiler chickens. One thousand unsexed day-old broiler chickens were assigned to five treatments : control(T1), 5ppm avilamycin(starter diet) & 5ppm flavomycin(grower diet) T2, 5ppm avilamycin(starter diet) & 50ppm CRINA$^{circledR}$(grower diet) T3, 50ppm CRINA$^{circledR}$(starter & grower diet) T4, 50ppm CRINA$^{circledR}$+ 500ppm lactic acid$^{circledR}$ (starter & grower diet) T5. Each treatment had four replications of 50 birds each. Growth performance was significantly improved by dietary supplements(T2-T5). There were no significant differences among treatment T2, T3, T4 and T5. Feed intake was not significantly different among treatments. Dietary supplementation of CRINA$^{circledR}$(T3, T4, T5) resulted in significant(p〈0.05) improvement in feed/gain(F/G) during finishing period (4-5weeks). The birds fed CRINA$^{circledR}$ supplemented diet(T4) showed significantly(p〈0.05) higher availability of crude fat, methionine and methionine + cystine than those fed antibiotics supplemented diet(T2). Mortality was not significantly affected by treatments. The colony forming unit(CFU) of E.coli in small intestinal content was significantly lower in antibiotics & CRINA$^{circledR}$(T3) compared to CRINA$^{circledR}$ treatment(T4)(P〈0.05). CFU of Cl. perfringens was low in CRINA$^{circledR}$(T4) but not different significantly with other treatments. Serum triglyceride level of birds fed CRINA$^{circledR}$ + lactic acid diet(T5) was significantly lower(p〈0.05) than those fed antibiotics supplemented diet(T2). Cholesterol level of the birds fed antibiotics(T2) or CRINA$^{circledR}$ + lactic acid supplemented diet(T5) was significantly higher(p〈0.05) than other treatments. HDL level of birds fed control diet was significantly lower(p〈0.05) than that of others. The levels of serum IgG were not significantly different among treatments. Major fatty acids composition of leg muscle fat was significantly influenced by treatments. Control group showed significantly higher palmitic acid(C$_{16:0}$) and steraric acid(C$_{18:0}$) content than other treatments(p〈0.05). Content of oleic acid(C$_{18:1}$), however, was significantly lower in the control than others treatments. Content of linolenic acid(C$_{18:3}$) was significantly higher in CRINA$^{circledR}$+ lactic acid(T5) than antibiotics & CRINA$^{circledR}$(T3) treatments. Total saturated fatty acids content was higher and total unsaturated fatty acids were lower in the leg muscle fat of the control than that of other treatments. It is concluded that CRINA$^{circledR}$ supplementation improved growth rate and F/G ratio in broilers. The combination of CRINA$^{circledR}$ with either antibiotics or lactic acid did not show any additive or synergistic effects in broiler chickens .