In the recent years have been set several requirements such as Mandatory external audit firm rotation and limiting the provision of non-audit services, to improve audit independence and audit quality. The purpose of this study is to investigate requirements effects in audit quality, users confidence, audit fees and it's cost-benefits. The data was collected by questionnaire that it was adopted in previous researches. The samples include 135 auditor and 77 investors (financial managements, experts, senior experts and investment analysts) in Tehran city. The results, showed that Mandatory external audit firm rotation and limiting the provision of non-audit services improve audit quality and users confidence. But, they do not have meaningful effect on audit fees. Also, there is no significant differences on auditors and investors attitudes about above requirements effects in audit quality and users confidence.