The structural characterization of protein α-helices is an important topic in structural bioinformatics. Hischenhuber et al. on page 1862 present a new methodology, based on differential geometric parameters, that compares helices to each other and determines the relative spatial orientation between two helices. The whole methodology is implemented in an easy-to-use, opensource Matlab package. The cover illustrates the ruled surface between the two α-helices of the homodimeric X-ray structure of the proto-oncoprotein MafA in complex with DNA (Protein Data Bank accession code 4eot).