The aim of this study was to analyze the effect of the adoption of Brazilian Accounting Standard - Auditing Technique 701 (NBC TA 701, in its Portuguese initialism) over the readability of audit reports. The study fills a gap in the literature by obtaining empirical evidence regarding the effect of NBC TA 701 on the readability and comprehensibility of audit reports. The study is important for verifying whether the disclosure of key audit matters (KAMs) improves the ease of reading and understanding audit reports after the adoption of NBC TA 701. Unlike in the previous literature, it was observed that the effect of KAMs has a non-linear, U-shaped relationship, which suggests additional benefits to readability based on a certain quantity of key matters reported. The data from a sample of 240 listed companies on the B3 S.A. -Brasil,Bolsa,Balcão (B3), in the period from 2013 to 2018, were assessed using content analysis, descriptive statistics, difference of means tests, and panel data correlation and regression analyses. The results showed that the adoption of NBC TA 701 significantly affected the Flesch readability index (FRI) of the independent audit reports. They also confirmed that the quantity of KAMs reported increases the FRI in a non-linear way, and that the types of key matters affect readability differently according to their complexity. The results provide evidence that the new audit report improves the level of readability in a non-linear way, thus contributing to the informational content of the audit report used by the various users for decision making.