Space biology and medicine is a relatively young field concerned with the study of the effects of the space environment (low gravity and radiation) on living organisms. Its beginnings may be set in the 1960's with the start of manned orbital flight. Until then animals were only used in ballistic flights (1948-1957) and early orbital missions (1957-1961) to ascertain the feasibility and safety of manned space travel.After the first manned spaceflight by Soviet cosmonaut Yuri Gagarin in 1961, the physiological effects of orbital flight, and particularly of long-duration space missions, began to be studied in more depth and more systematically. Human studies were conducted by the Unites States on the Mercuri, Gemini, Apollo, Skylab, and Shuttle missions. Animal studies were conducted on some of these manned flights and also on the unmanned Cosmos and Biosatellite voyages. While the more obvious effects of the space environment on humans and animals have been well documented in the last 30 years, much remains to be learned about their mechanisms and about possible countermeasures to these effects. In addition to the applied side of space biology and medicine, there are the fundamental questions of the role of gravity in the evolution, development, and reproduction of life on Earth - questions that can only be studied with the aid of space experiments. There is also emerging some potential usefulness of the low-gravity environment for cell separation and protein crystallisation.