The widespread ban on the use of some antibiotics as growth promoter has led to the search for alternative substances. In this study the efficacy of plant extract oregano as an alternative growth enhancer was investigated in three hundred day-old male Cobb chicks. The chicks were distributed following a completely randomized design into 3 dietary treatments: (1) basal diet, without supplement; (2) basal diet plus 250 ppm Oregano extract; and (3) basal diet with 50 ppm zinc bacitracin. Weight gains, feed consumption, feed conversion efficiency and mortality on days 1-21, 22-42 and 1-42 were recorded. At the end of the experiment, dressing percentage and economic evaluation were computed. Results of the study revealed that oregano extract significantly improved the average live body weight, weight gain and feed conversion efficiency of broiler birds, thus increasing performance. Oregano extract can also be a good substitute to feed antibiotics such as zinc bacitracin as growth enhancers for broilers.