The aim of this study is to examine whether gender diversity on audit committees influences financial reporting quality by using panel data of Spanish listed firms. The financial reporting quality of firms is measured by the type of opinion received in the audit report. We estimate various panel data models of audit opinions and control for factors that are traditionally found to impact audit opinions. This study provides evidence to support the hypotheses that the percentage of females on ACs reduces (...) the probability of qualifications due to errors, non-compliance or the omission of information. Furthermore, the results also find that the percentage of female directors on ACs, the percentage of independent female directors on ACs and ACs chaired by females increase the likelihood of further transparency by disclosing audit reports with uncertainties and scope limitation qualifications. (shrink)