this research aimed to study and test the impact of Audit firm's industry specialization and size on tax avoidance level for the Egyptian listed companies, using a sample of (98) non-financial companies listed on the Egyptian Stock Exchange belonging to (11) economic sectors, with a total of (294) observations during the period from 2016 to 2018, relied on a multiple linear regression model to test the hypotheses of the study, based on the dependent variable: (Tax avoidance level) Measuring by Two measures, the first: the difference between the legal tax rate applied in the country and the effective tax rate, and the second: the Effective Tax Rate "ETR" as an inverse measure of tax avoidance level, The independent variables: (Audit firm industry specialization Measuring by the market share,and Audit firm size Measuring by if it belongs or not belong to one of the big audit firms “Big4”), using: (Firm size, Rate of Return on Assets, Leverage, and the Company Industry type) as a control variables. The results of this research find: A positive effect with a statistically significant for the audit firm industry specialization at the companies tax avoidance level (acceptance The first hypothesis), and find A negative effect with a statistically significant for the audit firm size at the companies tax avoidance level (acceptance The second hypothesis), and find A positive statistically significant effect for each of (Firm size, Industry type) and a negative statistically significant effect for each of (leverage, and rate of return on assets) on the companies tax avoidance level.