In Switzerland, the use of International Accounting Standards (IAS) is allowed as an alternative to national rules for the preparation of consolidated financial statements. This opportunity has been widely used, since about 40% of Swiss listed companies do comply with IAS. Because of permissiveness and low disclosure requirements of the Swiss accounting regulation, compliance with IAS implies additional disclosure and renouncement of a considerable discretion in accounting practices. The aim of this paper is to determine the characteristics of firms which voluntarily choose to incur theses additional costs. On the basis of prior literature on voluntary disclosure and auditing, we formulate a set of hypotheses which are tested on a sample of 133 Swiss listed companies. The results suggest that political costs and pressures from outside markets play a major role in the decision to apply IAS but do not validate the hypothesis that voluntary compliance with stringent accounting standards is used to solve monitoring problems resulting from agency relationships between managers, stockholders and creditors.