An overview of the present state of aerospace medicine and planetary biology is given with emphasis on the ongoing search for extraterrestrial life and life science studies being made both by independent and cooperative investigations of the United States, the Soviet Union, the European Space Agency, and countries with an interest in gravitational physiology, radiation, planetary quarantine, exobiology, and general space biology. A suitable animal model for outer space medical research, in-orbit vestibular function investigations, biomedical problems in the Earth's normal 1-G gravitational intensity, and biological satellite experiments are discussed. The scope of exobiology, life detection programs, solar system organic chemistry, and attempted elucidation of the question of the origin and early evolution of life are also discussed. Evaluation of data acquired from a variety of sources indicates that all phases of exobiology lead to biopoesis and chemical evolution, with allied aviation, space, and environmental medicine being the major part of the search for extraterrestrial life.