Data on hospital antibiotic consumption in Germany is scarce and has been limited to a few analyses of expenditures done by hospital pharmacists or pharmacy committees. For national or international benchmarking strategies and interinstitutional comparisons it is necessary to estimate antibiotic use densities per 100 patient days and year, using the ATC/WHO-definition of daily doses (DDD). Since 2002 a research group of physician-scientists from the University of Freiburg, supported by governmental funds, has analysed antibiotic use density in hospitals. A major finding was that the commonly utilized DDD/100 data format may overestimate antibiotic use density in hospitals by up to 40% when compared with data using "recommended" (RDD) or prescribed daily doses rather than DDD. Furthermore the focus on patient days may be inadequate for monitoring trends over time given substantially changing lengths of stay and the increasing number of admissions. A new practical tool to overcome these limitations may be a special AccessXP database developed by the scientists from Freiburg. Using this database allows analysis of consumption data in either format, as DDD or RDD per 100 patient days or per admissions, if needed unit-wise or hospital-wide. In addition the antimicrobial drugs can be grouped as needed, and the data can be made available for different time periods, e.g. quarterly or yearly. This is expected to improve options to correlate consumption data with resistance data. Hospitals will benefit from this new tool, and hospital pharmacists are offered participation in a national surveillance programme.