The research aimed to measure the readability of the audit reports prepared and released by the Audit Office (AO) of Rio Grande do Sul, to examine the impacts of these documents on the judgments of the mayors made by the councilors. The applied methodology was the content analysis of the AO documents to measure the readability and then, a estimation was performed by logistics regression. The main results show that they were not found statistically a relationship between the technical documents sent by the AO to the municipal legislature and the judgments of the mayors. The research delivers an academic contribution, the analysis of the readability of the opinions of the AO, a starting point for future research in external control; It was delivered to AO, concluding that audit reports need quality to be well understood and thus become useful by the legislature.