The paper reviews technical trends in the development of life support systems for future manned space missions.Although open loop systems have been used to date, future designs for installations in permanent micro-gravity orbit, long duration transport and ultimately, lunar or planetary bases will rely on regenerative processes to reduce the penalties associated with on-board storage and the resupply of consumables from Earth. In the medium term, these processes will utilise physico-chemical methods, typically to recover metabolic oxygen from respiratory carbon dioxide and fresh water from contaminated water. Food and waste will continue to be treated as open loop consumables and expendables. Later, as sufficient terrain becomes available, lunar or planetary habitats will begin to use a combination of biologically derived and physico-chemical processes to process waste, recycle organic nutrients and produce food. The bulk production of food in a micro-gravity environment is considered to be impractical for reasons that are outlined in the paper.Factors affecting the selection of life support system designs are outlined briefly, candidate technologies for various sub-systems identified and process schematics for a number of systems including physico-chemical, controlled ecological and EVA portable life support are presented.