Using a sample of Italian firms publicly traded in the period 1996-2006, we analyze whether and to what extent the mandatory adoption of International Accounting Standards (IAS/IFRS) has affected the value relevance of different categories of intangible assets, such as goodwill, brands and patents, licenses, computer software, capitalized and expensed R&D. Prior literature claims that IAS adoption should improve the quality of accounting information and reduce information asymmetries. We find that IAS adoption has not enhanced the value relevance of intangible assets in general. This result may be ascribed to the obligation of expensing internally generated intangible assets and to the increased discretion in impairment test of goodwill. However, when we look at the value relevance of capitalized and expensed R&D, we find that the high uncertainty of future benefits of research costs negatively affects investors’ evaluation and, conversely, the high technological feasibility of development costs render and more valuable the information provided to investors.