This paper studies monopoly as an economic category. The research is mainly focused on the distinctive features of natural monopoly  as a type of monopolistic structure of the market economy. The author  came to the conclusion that the concept of natural monopoly remains to  be a disputable issue, since in spite of all advantages of the  productive efficiency, in the absence of competition there is a high  probability of the abuse of monopoly for the purpose of profit  maximization.  
In the beginning of new millennium the development of infrastructure,  international commercial relations, and information networks inexorably  involves creation, and development of the huge international companies.  The turnover of the biggest of them exceeds even the gross domestic  product of some countries. And there is nothing strange, that such  companies hold leading positions on national and international markets,  and at times, excluding competitors, become monopolists. 
 Company has a monopoly, if it is the only supplier of a product, and if  it does not have any substitutes. The principal reason for the  occurrence of monopoly is barriers at the admission to the market, which  do not allow other companies to compete with a monopolist. Such  barriers appear in following cases: only one company owns a key resource of manufacture; a government has given exclusive rights for manufacture of certain  production to one company; because of the production costs the highest efficiency of output is only  possible in the presence of one manufacturer on the market. 
The monopolistic market is considered to be the market of the seller.  The profits of the manufacturer are in this case guaranteed by the  production volume, and by the high prices. Actually, in the given  conditions the buyer is always forced to accept the price, which is  considerably above cost. 
There are very few examples of pure monopoly. It is rather one of the  ideal concepts, as far as all companies aspire to full monopoly, but  cannot reach it, or reach it only for a certain period. Though, this  rule has one exception- natural monopolies. In case of natural monopoly  the scale effect allows one monopolist to serve all market, having costs  lower, than in the presence of two or more competing managing subjects  in the given market. Such monopolist uses its resources the most  effectively. Being a large enterprise, it possesses high technical  equipment and big capacity. These factors conduct to the higher labor  productivity and the decrease of the product unit costs. Thanks to the  lowest possible cost price of the manufacture of the given goods,  natural monopoly is a desirable phenomenon for a society. Otherwise the  government interferes for the purpose of regulation of the monopolists  activity. Practically, the natural monopoly can be resulted by  availability of unique property (power supply systems, pipeline and rail  transport, unique natural resources, post), necessary for branches,  where long-term average costs are minimum only in case, when the market  is served by one manufacturer. 
The naturalness of monopoly can be determined by its attitude, or to be  more precise, by its fear of competition. Genuine natural monopoly  knows, that size matters, and if competitors enter the market, they will  not manage to seize the greater share. A typical example of all  mentioned above are railways in Sweden. The government of this country  conducted a classical vertical division into an infrastructure and rail  transportation, and the free competition in the market of transportation  was allowed. For 10 years the new companies managed to win from  monopoly only about 10 % of the market. The scale effect protects  monopoly better than any entry restrictions. 
Monopolies have natural advantages in those markets, where the action of  entire branch as a single mechanism is important. Though, such  situation can has its disadvantages.  Companies have no stimulus for  self-restriction of monopolistic abuse, since the client cannot leave  them for other competitors on the market. It often leads to such  inevitable consequences, as overpricing, uneconomical treatment of  expenses, indifference to the requirements of the clients, artificial  understating of the production volume,  and a full set of other  consequences of the monopoly, accompanied by ultrahigh monopolistic  profit earning. Such conditions indicate the classical fiasco of the  market, the contradictions, which the market is not able to overcome  without state intervention. For this reason in all countries natural  monopolies are either state companies, or are under tight state control. 
World practice of the state regulation of natural monopolies has more  than a century of history. In the USA, first federal control commissions  were set up in ХІХ century. For example, the Federal Power Commission  was organized in 1930. Today in the USA under the state regulation  remain such spheres of natural monopolies, as railway, aviation and  other types of transport; a number of fuel and energy manufactures (gas  supply, power generation); rendering of numerous public services. State  regulation concerns mainly those aspects of business activities in these  areas, which make a direct impact on the interests of the consumers:  price-level, production volume, bounds of the outlets, requirements to  the quality of the goods and services. The most widespread method is  that the prices of certain goods and services are established by state  structures. 
 Conclusion 
Natural monopoly in the market economy is considered to be a contradictory phenomena. As a type of monopolistic structure, it combines all negative displays of market monopolization, and can result the abuse of the unlimited market power. At the same time, acting as a necessary element of the production process, and representing socially significant branches of the national economy, the natural monopoly plays the important positive role in the market economy. The state regulation of natural monopolies should be aimed first of all at the termination or control of price growth of the natural monopolies production on the domestic market, and simultaneous preservation of these prices at the level, which allows extended reproduction. In this case the national policy can ensure further prosperity of both monopolies and citizens of the country.
Natural monopoly in the market economy is considered to be a contradictory phenomena. As a type of monopolistic structure, it combines all negative displays of market monopolization, and can result the abuse of the unlimited market power. At the same time, acting as a necessary element of the production process, and representing socially significant branches of the national economy, the natural monopoly plays the important positive role in the market economy. The state regulation of natural monopolies should be aimed first of all at the termination or control of price growth of the natural monopolies production on the domestic market, and simultaneous preservation of these prices at the level, which allows extended reproduction. In this case the national policy can ensure further prosperity of both monopolies and citizens of the country.