The reduction of tropical forests has generated a loss of ecosystem services across the globe. In Brazil, essential biomes related to water provision (such as the Atlantic Forest and Savanna) have been degraded, compromising water-ecosystem services. Payment for water- ecosystem services (water PES) has been implemented as a tool to stimulate changes in the use and management of these areas. Many water PES projects have emerged in Brazil using forest restoration, aiming to improve water ecosystem services. In this context, this study identified the types of monitoring carried out in Brazilian water PES projects, to include their main characteristics and gaps. Five Brazilian projects were selected for analysis as case studies. Interviews were then conducted with stakeholders to get current data on their monitoring practices. The data from the literature review, case study approach, and interviews were analyzed from the perspective of monitoring guides recommendations. Different aspects were analyzed, such as objectives, institutional arrangements, type of monitoring, indicators, and frequency of monitoring. The study indicates that there is a lack of standardized methods, making it difficult to specify the results of the implemented actions. The central gap is related to benefit monitoring. It is necessary to establish a holistic monitoring system, dealing with the ecosystem as a complex socio-ecological system. Some perspectives to solve the problems were proposed. The results of this work may help not only improve the current and future PES schemes in Brazil but also in other countries, especially developing ones, where vulnerable populations depend upon them.