We used genetic data from 7 microsatellite loci to determine the frequency of multiple paternity in clutches of giant Amazon river turtles, Podocnemis expansa, from the Orinoco River in Venezuela. Among hatchlings sampled from 32 clutches, paternity analysis found that a minimum of 10.3% could conclusively be shown to have been sired by more than one male. We contrast this result with those from another population of this species, as well as other species of turtles, and discuss the importance of documenting patterns of paternity in different populations of a given species and considering the effects of ecological differences among populations on female mating behavior.