This research investigates the relationship between auditor’s opinion and stock return in the companies listed at Tehran stock exchange market. In this study, all required data are collected from aware shareholders and provide a sampling of 130 questionnaires, the data collected over the period 2010-2011 using test methods such as computer software, data analysis and statistical methods to answer research questions. According to research result through questionnaires and tests, there is a significant relationship between stock returns and the auditor & apos; s opinion, in fact, for aware shareholders of the company the auditor’s opinion has a special message. This message is based on the results of study hypothesis in comparison with previous research with regard to changes in the questionnaire and provides assumptions that are more detailed. The first finding is that unqualified audit report has a positive impact on stock returns of companies with a medium to low degree. Adverse audit report has a negative impact on stock returns of companies with medium to high degree. Disclaimer of audit report has a negative impact on stock returns of companies with medium to high degree. Finally, qualifying paragraphs, which modified the items of income statement items have more impact in comparison with qualifying paragraphs which modified the Balance Sheet items.