In this research we attempt to examination the relation between some factors such as Institutional ownership, non duty managers internal auditing, and economic characteristics, including firm size, financial leverage, profitability, growth opportunities, and also size of auditing firm with voluntary disclosure in the annual report in industrial corporation of Tehran stock Exchange. For this aim, 97 of corporation that published financial reporting in end of 2010 were selected.
Voluntary disclosure by an index consisting of 70 items was determined and possible association with independent variables by using the multiple regression analysis was performed.
The results show that the model explanations 30.8 percent of voluntary disclosure variations.
The test of hypothesis show that there is a positive relation between internal auditing, firm size and institutional ownership with voluntary disclosure but this relation between size of auditing firm and voluntary disclosure is negative and there is no relation between other variables with voluntary disclosure.