: Data quality (DQ) is emerging as a new relevant area for the improvement of the effectiveness of organizations. Despites the consequences of poor quality of data are often experienced in everyday life of enterprises, very few organizations adopt specific methodologies for assessing and monitoring quality of their data. In this paper we present the first results of an Italian project whose goal is to produce an enhanced version of well known approaches to Basel II operational risk evaluation, with a significant relevance to information and data quality, and its effects on operational risk. In particular in this paper we focus on the definition of an assessment methodology and a supporting tool for DQ. Key Words: Data quality, Data assessment, Methodology, Tool for data assessment