Biobanks store and manage collections of biological material (tissue, blood, cell cultures, etc.) and manage the medical and biological data associated with this material. Biobanks are invaluable resources for medical research. The diversity, heterogeneity and volatility of the domain make information systems for biobanks a challenging application domain. The European project BBMRI (Biobanking and Biomolecular Resources Research Infrastructure) has the mission to network European biobanks, to improve resources for biomedical research, an thus contribute to improve the prevention, diagnosis and treatment of diseases. We present the challenges and discuss some architectures for interconnecting European biobanks and harmonizing their data.