This report consists of a collection of 225 abstracts of radiation research sponsored by NASA during the period 1986-1990. Each abstract has been categorized within one of four discipline areas: Physics, Biology, Risk Assessment and Microgravity. Topic areas within each discipline have been assigned as follows: Physics--Atomic Physics, Nuclear Science, Space Radiation, Radiation Transport and Shielding and Instrumentation: Biology--Molecular Biology, Cellular Radiation Biology, Tissue, Organs and Organisms, Radioprotectants and Plants: Risk Assessment--Radiation Health and Epidemiology, Space Flight Radiation Health Physics, Inter- and Intraspecies Extrapolation and Radiation Limits and Standards; and Microgravity. When applicable subareas have been assigned for selected topic areas. Keywords and author indices are provided.