Abstract The authors compared the first phalanx of the second wing finger of 33 European diurnal raptors. The importance of studying this bone lies in the fact that, although it has diagnosable characteristics, it was practically neglected by osteologists and paleontologists. Thus, fossil materials can be identified through them, as well as those from owl pellets. The comparison was made possible by the comparative avian skeleton collection of the Hungarian Natural History Museum. In a preliminary investigation we examined the morphological diversity of the first phalanx of the second wing finger among the different species. We used principal component (PC) analyses on measurements. The PC described the curvature of the anterior surface of the bone and the relative size of the distal and proximal epiphyses. The principal component analysis showed slightly overlapping in shape between the taxons but the accipitriform and falconiform birds diverged in the morphospace. The attributes and geometry of the first phalanx of the second wing finger reflects more on taxonomic background than flying behaviour. The avian wing is a complex and highly modulable structure, therefore, probably body mass and size affect flying performance than the other morphological features of this bone. The text is supplemented by 6 figures and one size table.