The study primary purpose is to determine the nature of the relationship between brand authenticity (BA) and customer brand engagement (CBE), Moreover, identifying the nature of the relationship between brand authenticity and marketing agility (MA),in addition to, disclosing the relationship between marketing agility and customer brand engagement, and finally, identifying the mediator role of marketing agility in the relationship between brand authenticity and customer brand engagement for Egyptian telecom companies.in addition to, disclosing the relationship between marketing agility and customer brand engagement, and finally, identifying the mediator role of marketing agility in the relationship between brand authenticity and customer brand engagement for Egyptian telecom companies.in addition to, disclosing the relationship between marketing agility and customer brand engagement, and finally, identifying the mediator role of marketing agility in the relationship between brand authenticity and customer brand engagement for Egyptian telecom companies.in addition to, disclosing the relationship between marketing agility and customer brand engagement, and finally, identifying the mediator role of marketing agility in the relationship between brand authenticity and customer brand engagement for Egyptian telecom companies.in addition to, disclosing the relationship between marketing agility and customer brand engagement, and finally, identifying the mediator role of marketing agility in the relationship between brand authenticity and customer brand engagement for Egyptian telecom companies.