The question of investing a lot of money by business entities in the development and operation of information systems in comparison with their economic gains is a long-term problem, depending on several factors. The problem is being solved by many authors as well as company's experts in information technologies. From analysis of heavy expenses of the information systems in the agriculture sector, conclusions can be drawn about financial gain from these systems used in different conditions of agricultural production, among which are cost amount, quantification of economic gain and assessment of risks that may cause the information system collapse. Using the coefficient of economic efficiency of an information system, it is possible to determine in particular companies what sort of quantified effects can be attained (a plan) or have been attained (reality) per Slovak koruna of expanded one-time investment. A number of years that this investment needs repaying can be calculated by the indicator of a period of return on investment in the company's information system.