Essential oils (EO) are importance aromatic components of herbs and spices, such as oregano, thyme, basil, lemon and eucalyptus. Beneficial effects of EO in animal nutrition may include the stimulation of appetite and feed intake, stimulation of endogenous digestive enzyme secretion, antibacterial, antiviral, respiratory system and stimulation of immune. Adding EO to diet or drinking water of broilers as alternatives to antibiotic in animal feed. The results of this reviews showed that EO causes to weight gain and FCR improvement. The uses of combination of EO are more effective effects for performance and decreased respiratory diseases of broilers.