Tourism has been identified as an activity that promotes sustainable development and as a business option consistent with the principles of biodiversity conservation. In spite of this, tourism can also be a transforming force in natural ecosystems. Because of this environmental certifications have been created in order to inform consumers about the sustainability achievements of this industry. The biodiversity conservation component is evident both in the definition and promotion of ecotourism, as well as in the principles of certification, but there are no efforts aimed at verifying the true scope of certification as regards the conservation of biodiversity. This work aims to determine the scope of ecotourism certification as a tool for biodiversity conservation and to achieve this was chosen the Certificate of Sustainable Tourism (CST) of Costa Rica. To achieve this, the research was divided into three phases: Analyze the purposes of tourism certification in Costa Rica; Analyze the processes that the hotels carry out to obtain certification aimed at the conservation of biodiversity; and, Evaluate the effect of ecotourism certification on attributes of biodiversity.