Nest site characteristics and reproductive success of Black-crowned Night Herons Nycticorax nycticorax, Little Egrets Egretta garzetta and Grey Herons Ardea cinerea were studied in a heronry in Pyeongtaek, Gyeonggido, Korea. When the species nested in trees without other conspecifics, the mean height of the nest from the ground and the mean distance of nest from the tree trunk differed among species. In trees where both Black-crowned Night Herons and Little Egrets nested, mean nest height did not differ between species, but Black-crowned Night Herons nested, on average, farther from the tree trunk. In trees where Black-crowned Night Herons and Grey Herons nested, the mean distance of nest from the tree trunk for Black-crowned Night Herons was greater, but the mean nest height did not differ between species. In trees where all three species nested, the mean nest height from the ground for Black-crowned Night Herons and Grey Herons was higher than for Little Egrets, and the mean distance of nest from the tree trunk for Black-crowned Night Herons was greater than for the other species. Clutch size did not differ significantly among herons and egrets. Black-crowned Night Herons had fewer hatchlings and fledglings than did the other species. We suggest that while nest height from the ground for herons and egrets was not related to reproductive success, the distance of the nest from the tree trunk was so related.