In the past, production in enterprises with high concentration of capital was a major characteristic of the Ukrainian economy. The transition to a market economy on the basis of private ownership led to the emergence of a large number of business entities, which are classified according to the economic criteria as small businesses. In this paper we examine the economic nature of business, small business and entrepreneurship. In scientific literature there is often presented an argument about the advantages of the economy of scale. Empirical evidence shows that the advantage of a large business in comparison to a small one in the agriculture is not absolute. The advantages and disadvantages of small forms of management are given in this paper. We analyze the quantitative criteria for the division of enterprises to large, medium, and small. They are represented in various legislative acts of Ukraine; however they do not always correspond with each other.