This research aimed to study and test the impact of audit quality on the relationship between managerial ability and investment efficiency for the Egyptian listed Companies, using a sample of (100) non-financial companies listed on the Egyptian Stock Exchange belongs to (14) economic sectors, with a total of (464) observations during the period from 2015 to 2020. The results of this research found: A positive and significant relationship between managerial ability and investment efficiency, A positive and significant impact of audit quality measured by (Audit Firm Size, and Auditor Industry Specialization) on the relationship between managerial ability and investment efficiency, The results showed an increase in the investment efficiency in companies with high managerial ability and audited by auditor's belonging to (Big4) and specializing in auditing the industry to which these companies belong, The results also indicated that there is a positive and significant relationship between company's size and the investment efficiency, and a negative and significant relationship between each of (Leverage , Rate of return on assets, Industry type) and investment efficiency