This paper aims to identify the factors that influence the type of opinion issued by the auditor in the Audit Report of companies listed on Euronext Lisbon. The data were collected from the Reports and Accounts and the respective Audit Report of the companies listed on Euronext Lisbon for the period from 2018 to 2022. After content analysis, the data were statistically processed through bivariate statistical analyses. It was found that, of all the variables analyzed, the audit fee variable and the type of audit firm variable influence the type of opinion issued by the auditor. That is, when the fees are higher, there is a greater probability of issuing an unmodified opinion. In addition, companies audited by Big Four firms are more likely to receive an unmodified opinion.