Nature reserves represent the highest form of nature conservation. The network of nature reserves within the Soviet Union was established gradually on a scientific basis and in accordance with the plans of the state and the individual Union republics. In the Soviet Union, a firm and progressive understanding of the status of state nature reserves has been established. Unlike the national parks common in other countries, any economic activity is prohibited within our nature reserves. Large-scale, unorganized visits by non-specialists, including tourists, are also not permitted (special routes are designated for tourism purposes). Nature reserves are typical natural areas maintained in their natural and pristine state. They are essential for the preservation of natural ecosystems, flora and fauna, and for the study of natural processes under conditions free from human interference. Such reserves have now begun to be referred to as biosphere reserves. An essential requirement is that scientific research must be conducted within nature reserves, the most important component of which is the "Chronicle of Nature" - continuous year-round observations of major natural phenomena and objects. Observations under the "Chronicle of Nature" program in nature reserves began more than forty years ago at the initiative of the distinguished ecologist and naturalist Professor A. N. Formozov. In essence, the simple yet profound concept of the "Chronicle of Nature" already contained the theoretical and practical foundations of what is now widely applied in world science as biosphere monitoring, that is, a system for monitoring the state of the biosphere. This book is a reference handbook containing brief information on 127 nature reserves and reserve-hunting areas in the Soviet Union. The reserves are described according to the Union republics in which they are located. The brief descriptions were prepared according to a unified scheme; however, because information on some reserves was insufficient, this scheme could not always be followed strictly. Overall, the book has the character of a register. This point deserves emphasis, since the concept of a register of state protected areas, including nature reserves, has only recently begun to gain recognition. The idea of creating biological registers originated in the Nature Conservation Center Laboratory and is currently being developed at the All-Union Research Institute for Nature Conservation and Nature Reserve Affairs of the USSR Ministry of Agriculture, which is being established on that basis. In preparing this book, the authors made use of published literature, primary sources, and departmental materials. In particular, for many reserves, especially those established recently, data were obtained from the nature conservation authorities of the individual republics. Foremost among these was the Main Administration for Hunting and Nature Reserves under the Council of Ministers of the Russian Soviet Federative Socialist Republic.