The aim of this study is to analyze the influence of market structure on audit fees, based on industrial economics theories. Method: We use a Ordinary Least Squares (OLS) model in which audit fees is a dependent variable and concentration measures, market share and leadership, and a proxy for audit quality are the main independent variables. The population was composed by the companies listed on Brazil Stock Exchange-B3, from 2010 to 2015, resulting in a sample with 1,663 observations in the period. Originality/Relevance: This research explores different metrics of market structure and control variables for a sample and period not previously analyzed in the Brazilian literature. The article addresses a relevanttopic for competition regulatory agencies, clients of audit firms and external users of financial statements. Results: The results confirmed the hypothesis that there is a positive relationship between market concentration and the audit fees, even when considering only the group of big firms. Evidence shows the existance of value to the brand and possible search for quality in auditing by publicly traded companies. We also found a positive relationship between audit fees and earnings management, contrary to the predicted hypothesis. Theoretical/Methodological contributions: The results showed that firms with higher market share charged higher audit fees to their clients. Among the big firms, the leader has significantly higher audit fees than the other firms. In addition, the positive relationship between audit fees and earnings management may mean that the audit firms charge higher amounts for those clients who practice management more intensively.