Morphology, anatomy, and ultrastructure of nectaries of 12 species belonging to five tribes of Rhamnaceae (Pomaderreae, Colletieae, Paliureae, and Gouanieae of the Ziziphoids clade and Rhamneae of the Rhamnoids clade) were studied by light and electron microscopy. Four types of nectaries were observed in this study. Species of the tribes Rhamneae, Gouanieae, Paliureae, and Cryptandra tomentosa Lindl. of the Pomaderreae tribe have annular nectaries. Siegfriedia darwinioides C.A. Gardner and Stenanthemum humile Benth. (Pomaderreae) have revolute nectaries, as do Colletia paradoxa (Spreng.) Escalante and Colletia spinosissima J.F. Gmel. (Colletieae). Retanilla patagonica (Speg.) Tortosa and Kentrothamnus weddellianus (Miers) M.C. Johnst. (Colletieae) have indistinct and adpressed nectaries, respectively. Nectar secretion occurs through modified nectary stomata in all species. Differences in the ultrastructure, mode of nectar secretion, and position of the nectaries are discussed. According to the organelles found in the nectary cells of all the species studied, granulocrine secretion is most likely to occur. Further research on these structures in additional species of this family could help to establish nectary homologies.