Herons and bitterns are medium to large sized birds of the family Ardeidae. With long bills, neck and legs they are adapted for wading and feeding on fishes and other kinds of small animals that occur near water. They live in all regions of the world except Antarctica. Traditionally, the family is included in the order Ciconiiformes, together the Scopidae (hammerheads), Threskiornithidae (ibises), Balaenicipitidae (whalebills) and Ciconiidae (storks). However, some authors have proposed a new order, Ardeiformes, for these birds. Another taxonomic problem in the family Ardeidae concerns the validity and the limits of some genera. This study presents a new approach to the morphology, mainly of the skeleton, of this group looking for new data that may provide insights for the taxonomy of this family. Sixty six complete skeletons of Ardeidae, representing 13 genera and 22 species were studied. Our studies indicate that the species Syrigma sibilatrix and Pilherodius pileatus have sufficient characters to be maintained in their monotypic genera within the subfamily Ardeinae. Egretta Alba has several characters that support its inclusion in the genus Ardea, as Ardea Alba. Butorides and Bubulcus also have particular features that are valid and monotypical. For Cochlearius, it is very clear that it is an Ardeidae, and despite its special bill and skull structure, it must be included in the night-heron group (Nycticoracinae). The genus Nyctanassa is another valid genus and differs from species of the genus Nycticorax in several osteological characters. The classification of the Ardeidae by Martinez-Villalta & Motis (1992) is the most consistent with this study, in spite of some differences, and that the family Ardeidae should be divided in four subfamilies: Ardeinae, Nycticoracinae, Tigrisomatinae and Botaurinae