Estimation and forecasting of social and economic development is among the problems which decision is of great importance for functioning of economy of any country. Now in Russia necessary scientific maintenance of scenario planning is created, and the Government of the Russian Federation has passed to working out of scientifically wellfounded intermediate term scenarios of development of a national economy and regions. However developed scenarios concern usually only two variants:Inertial and innovative. Working out of scenarios of functioning of economy in the conditions of crisis is absent. At crisis approach especially it affects economy of regions and development of territorially - branch complexes. In article« Scenario planning of development of regional branch complexes as the tool of prevention of negative consequences of crisis »the estimation is given scenario planning of economy of regions of Russia, the effective tools used at scenario planning which application is necessary for using for prevention of failures in work in a crisis situation. The special attention in article is given working out of lookahead scenarios of social and economic development of branch regional complexes, and also application in scenario planning of the mathematical models developed in Russia.