As part of our study on coppery titi monkeys in the Peruvian Amazon, we observed an individual rubbing his belly with leaves from a potentially medicinal plant. He climbed down from high above and grabbed a handful of leaves from an understory tree, which made it look like a deliberate action. Sitting on a liana he then chewed on the leaves before rubbing them slowly on his belly for a couple of minutes. The plant genus is known in traditional medicine and is used for various effects.