Ecology studies on Phrynops hilarii in their natural habitat are rare, and they are nonexistent in Santa Catarina State. This species was studied in the restinga of the Serra do Tabuleiro State Park from July 2004 to December 2005. Five examples of oviposition were registered, and also eggs predation by Tupinambis merianae. Thirteen adult specimens were measured. In general, the results corroborate and/or add to existing knowledge of P. hilarii biology, especially in relation to areas of restinga.