The NASA Lyndon B. Johnson Space Center (JSC) Life Sciences Space Station Program (LSSSP) will support the NASA goal of expanding human presence beyond the Earth into the solar system. The Biomedical Research Project (BmRP) is a major element of the LSSSP and is planning an onboard laboratory for studying the effects of microgravity on humans. During the Space Station era, the major emphasis for the BmRP is to identify and quantify the effects of reduced gravitational forces on humans and, if necessary, to develop methods and techniques which counteract or modify these effects to promote man's long-term health and productivity while working in space and upon return to Earth. A status of current science, technical, and programmatic planning activities that are being conducted at JSC to define BmRP requirements for the Space Station Program is presented herein. Included is a discussion of a representative scenario of biomedical investigations and associated engineering analyses that are being developed as a model of the types of studies and resources which will be used on the Space Station. The evolutionary process used in identifying scenarios and associated requirements relative to Space Station is also discussed.' These initial planning activities, representative scenarios, and engineering analyses form the foundation for the life sciences Biomedical Research Project requirements.