Regarding molecular biology, we see an exponential growth of data and knowledge. Among others, this fact is reflected in more than 300 molecular databases which are readily available on the Internet. The usage of these data requires integration tools capable of complex information fusion processes. This paper will present a novel concept for user specific integration of life science data. Our approach is based on a mediator architecture in conjunction with freely adjustable data schemes. The implemented prototype is called BioDataServer and can be accessed on the Internet: http://integration.genophen.de. To realize a comfortable usage of the resulted data sets of the integration process, a SQL-based query language and a XML data format were developed and implemented.