The evolution of investment as an important economic category is discussed in this article. The different definitions of investment exist in a lot of sources of special literature. Some authors consider that investment is the placement of capital in some production only. Others defined the investment as a investment of money only, through investment are known in the material form too. The third group of scientists considers investment as input of capital for a long time, but in practice of enterprises often it is necessary to input financial resources in some means that will be used in the short time – such as raw materials, semi-finished products, combustible, seeds and others. Later some authors have generalized different views on the conception of investment and proposed one overcomes shortcomings. In their opinion the investments may be characterized as a capital in different forms, placed in different projects that has goal to receive income profit and others utile effects. Moreover the micro – and macroeconomic approach is known in the treatment of investments. Also the investments are defined in economic account and financial sense. The author of this article has examined a lot of investment conceptions and has proposed the own idea. The author characterized investment in the enterprises as capital input in different forms to increase the efficiency of production and to receive some other noneconomic results.