Ecological tourism is a rapidly growing type of tourism. The term "ecotourism" is often used by marketers to attract tourists. In modern practice the concept of ecotourism is often distorted due to either ignorance of its essence or in favor of development of tourism business. The authors study the key functions of ecotourism and different approaches to their classifications. In the given research they identify the recreational, educational, environmental and economic functions of ecological tourism and analyze their specificity. The focus of recreational function of ecotourism is restoration of physical and mental powers of man in natural surroundings by means of various types of active and passive recreational activities. The environmental function lies in prevention or minimization of negative impacts and consequences of tourism activities in fragile natural areas. Different tools are applied for this purpose such as strict regulation of types of impacts, defining permissible norms of recreational loads, zoning, construction of trails and facilities. The article also gives examples of the positive effect of ecotourism in the recovery of some animal species. Environmental education has indirect but not less important impact on natural systems by forming ecological ethics in tourists and the changing stereotypes of their behavior by increasing the level of environmental awareness (educational function). Economic function of ecotourism gives benefits to local communities together with financial incentives for nature protection in their region. The authors discuss various experiences in the field of ecotourism in different countries and analyze forms and peculiarities of the implementation of these functions.