A hypothesis on financial accounting disclosure practices has been established in prior literature. The hypothesis was that financial accounting disclosure practices are not arbitrary, but are influenced by company characteristics and corporate governance. In order to examine the validity of this hypothesis, two disclosure indexes were built using as sample the published Annual Reports for 2004 of all the listed manufacturing and construction companies in the Athens Stock Exchange (ASE). The first index contains items which are mandatory according to Greek General Accepted Accounting Principles (GAAP); and the second index contains items which are mandatory according to a number of selected International Accounting Standards (IASs) but which were voluntary at the time that the research was conducted. The study used a cross-section model, in which each type of disclosure index was regressed on proxy-related variables with corporate governance and voluntary disclosure in order to detect the existence of a statistically significant relationship. The major finding of this research is that there is a significant extent of noncompliance in respect of IASs and the disclosures of Greek regulations. The key factors associated with the levels of compliance with IASs include the composition of the Board of Directors, profitability and the number of common shares. The public firms in the sample have shown that because of the political cost, the management is forced to disclose accounting data and support transparency.