Hep-Net is a German medical research and health care network dedicated to viral hepatitis. Its many activities include basic and clinical research, training and public awareness, and rely on modern information technology and the Internet. One major component is a central registry for medical data, serum and tissue samples. In order to build this registry, important legal and technological issues needed to be addressed. Specifically, commercially available electronic data capture systems for clinical trials are generally ill suited for this purpose. The framework of the solution described here may be the basis for similar networks dedicated to specific disease entities or other phenomena.