This paper conducts an exhaustive bibliometric and bibliographic review on the analysis of methodologies for the economic estimation of indicators in environmental conservation, with special emphasis on the estimation of opportunity costs. The results reflect a growing trend in academic activity related to this topic, with an average growth rate of approximately five articles per year since 2005. This increase demonstrates a global interest in the study of economic methodologies applied to conservation, driven by the growing need to integrate economic criteria into natural resource management. Although many of the studies originate in Chinese and North American academic institutions, most of the case studies focus on the Amazon region, a critical area for global conservation. The evolution of academic thinking in this field has gone through several stages, starting with a focus on environmental protection, then expanding to biodiversity conservation, ecosystem services and, more recently, payments for these services. Within this framework, the estimation of opportunity costs has emerged as a fundamental tool to motivate conservation, especially in rural contexts where communities can be encouraged to participate in environmental protection programs. This methodology not only helps to quantify the economic benefits of conservation, but also promotes more equitable and sustainable policies.