The purpose of International Financial Reporting Standards (IFRS), adopted mandatorily by European listed firms in 2005, is to increase the transparency and the comparability of accounting information, which should have led to improvements in these firms’ information environments. This study uses market microstructure proxies for information asymmetry to examine the effects of IFRS adoption on the level of information asymmetry in the Spanish stock market. Therefore, we consider a setting with substantial differences between local standards – Spanish Accounting Standards (SAS) ‒ and IFRS and where the level of enforcement is low. By controlling for conventional determinants of information asymmetry and firms’ characteristics that influence their information environments, we find a reduction of information asymmetry after IFRS adoption. Our findings suggest that the mandatory switch from local accounting standards to IFRS conveys benefits to the market, even when the enforcement level is not strong.