The European Space Station (ESS) will permit crews of up to six to participate in low-orbit missions of extended duration. The character of the crews is expected to change from the pilot astronauts to scientist-technicians. As a consequence to this change in scope, ESA will probably not be able to rely on a small community of physically top-fit astronauts. The crew's physical condition will certainly vary as the individuals' professional skills will greatly influence crew selection at the expense of physical excellence.The paper presents results of a health risk analysis and the subsequent derivation of medical requirements. A discussion follows comprising the definition and analytical accommodation of medical equipment as well as an estimate of overall Health Care System (HCS) mass, volume and power requirements.The paper is subdivided into 3 sections: health risk assessment, medical equipment definition and health care system design.