This study investigated the influence of oregano essential oils (OEOs) as common development promoters on the growth performance and cost economics of broiler chicks, 180 one day old chicks (Ross 308) classified into 3 groups (3 replicates /20 birds /replicate). The experimental groups were as follows: group (1) control (basal diet), group (2) basal diet + 300 µl oregano essential oils extract per kg diet and group (3) basal diet + 600µl oregano essential oils extract per kg diet. The experiment lasted for 35days. Results showed that the body weight and weight gain of chicks fed diet contained 600 µl oregano essential oil / kg basal feed was higher significant (P≤ 0.05) than that fed diet contained 300 µl OEOs group and control group. Whereas feed consumption in the oregano supplemented groups was lower (P ≤ 0.05), resulting in a significantly increased feed conversion (P ≤ 0.05). The European chicken index increased in the group receiving 600 µl of OEOs compared to other groups. There was no significant change in feed cost between the supplemented and control group, but the group supplemented with 600 µl of OEOs showed greater growth and thus better net return. Also, the economic efficiency showed a greater difference in the 600 µl OEOs supplement group. It could be concluded that the use of 600 µl OEOs improved the overall performance and economic efficiency of broilers; therefore it could be supplemented to broiler chicks.