•New data on Hg in tissues of green turtles from the South Atlantic Ocean.•A nonlethal/noninvasive method is assessed for Hg monitoring in sea turtles.•We found positive correlations between Hg in muscle and scutes, liver and kidney. The green sea turtles are facing a very high risk of extinction in the wild and the impacts of heavy metals contamination contributes with the decline of their populations. It is very important to assess noninvasive and nonlethal methods for monitoring Hg contamination in sea turtles. Thus, Hg concentrations were measured in keratinized fragments (scutes) and internal tissues of green sea turtles from the Ceará coast to test the usefulness of scutes as a monitoring subject for sea turtles. A significantly positive correlation was found between Hg concentrations in muscle and scutes, which demonstrate that scutes can be used as a predictive matrix of Hg concentration in muscle tissue of green sea turtles.