It is generally recognized that in long-term space flights it is necessary to create an environment adequate to human requirements. Such environment can be created using biological life-support systems of which the main component are higher plants.The investigations were carried out with plants in different morphological forms: seeds, tubers, bulbs, seedlings, vegetating plants. An integral effect of space flight factors has been estimated in plants on the subcellular, cellular and organism levels. Changes in the composition of photosynthesizing pigments, carbohydrate metabolism and mineral composition have been revealed.One of the main results of plant investigations is that they have proved the possibility for plants (e.g. Arabidopsis and wheat) to experience the whole cycle of ontogenesis under microgavitational conditions.