The syrinx is the organ responsible for producing the vast majority of bird sounds. Because its anatomy varies greatly among bird taxa, prior knowledge of variations is extremely important to studies of functional anatomy and phylogenetic systematics. With the aim of accessing and describing morphological variation in birds of the tribe Arini, this paper presents the findings of a comparative analysis of the syrinxes of 156 specimens belonging to 47 species in 22 genera of the tribe. A number of hitherto unknown variations are highlighted and confronted with the knowledge produced to date on the morphology of the syrinx in Psittaciformes. Some of the variations detected occurred in structures probably involved in sound production and this should be taken into consideration in future studies of functional anatomy. Several characters suggest the presence of a phylogenetic signal, given the congruence between their distribution among taxa and the hypotheses regarding monophyletic groupings proposed in the literature. Some of the variations found, including those suggesting a phylogenetic signal, are intraspecifically polymorphic, which reinforces the importance of using series of specimens in studies of syrinx anatomy.