This study was aimed to determine the effect of different levels of clove extract supplementation in diets on performance and nutrient digestibility in broilers and to determine whether it could be alternative to antibiotics or not. Three hundred (3-day-old) commercial broiler chicks (Ross–308) were divided into groups of 60 birds in each and randomly assigned to the five treatment diets with three replicate. Birds were fed basal diet or the basal diet supplemented with 100, 200, 400 ppm of clove extract and 10 ppm avilamycin. Experiment was continued 42 days. There were differences in body weight and daily body weight gain at 7. and 21. days measurements in 400 ppm clove extract and antibiotic supplemented groups but differences of the other periods were not statistically important. There was difference in daily feed intake in 400 ppm clove extract and antibiotic supplemented groups at 4. week of the experiment but differences of the other weeks were not statistically important. The best feed conversion ratio was in 400 ppm clove supplemented group and there were statistically important differences in feed conversion ratio among groups. The best digestibility degrees were in 400 ppm clove supplemented and antibiotic groups, then 200, 100 and Control groups followed them respectively. Clove extract has the positive effects on performance and digestion process and it is natural and safety feed additive so that 400 ppm supplementation of clove extract to diets can be considered as an alternative natural growth promoter for poultry instead of antibiotics.