Purpose:This paper aims to examine the effect of qualified auditor opinion on the relationship between Book-Tax Differences (BTDs) and firm value in Egypt. Design/methodology/approach:We investigate a sample of the Egyptian firms listed on the EGX100 index; during the period of 2014-2018. The final sample was 335 firm-year observations. The data was analysed using OLS regression. Findings:The results show a significant negative relationship between BTDs and firm value. We also find a significant moderating role to the qualified auditor opinion on the said relationship, as we find that the negative relationship occurs only in firms with qualified audit opinion. Originality/value:To the best of authors'knowledge, this is the first study that examines the moderating role of qualified auditor opinion on the relationship between BTDs and firm value in Egypt. The results confirm the growing concern of investors about the BTDs for the firms with qualified auditor opinion. Therefore, our results may be interesting to managers, researchers, investors, auditors, and regulators, who care of the potential implications of BTDs when coincide with qualified auditor report.