Rational drug design is an example where integrated access to heterogeneous scientific data is urgently needed, as it becomes rapidly available due to new experimental and computational techniques. This is currently problematic as data is scattered over heterogeneous, mostly file-based legacy databases, the data is erroneous, incomplete, and inconsistent in representation and content. We have developed a methodology, including metadata specification, data transformation and software architecture, that supports data analysis and preparation for building a data warehouse using object-oriented database technology. With this methodology the system ReLiBase has been realized, that allows querying and visualization of the drug-design related data from heterogeneous resources.